diff --git a/cal.c b/cal.c
index 5b845fd..8b5244c 100644
--- a/cal.c
+++ b/cal.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
@@ -10,7 +9,7 @@
 
 static void drawcal(int, int, int, int, int, int);
 static int dayofweek(int, int, int, int);
-static bool isleap(int);
+static int isleap(int);
 static void usage(void);
 
 static void
@@ -59,7 +58,7 @@ drawcal(int year, int month, int day, int ncols, int nmons, int fday)
 				cur = moff % 12;
 				yoff = year + moff / 12;
 
-				ndays = mdays[cur] + ((cur == 1) & isleap(yoff));
+				ndays = mdays[cur] + ((cur == 1) && isleap(yoff));
 				day1 = dayofweek(year, cur, 1, fday);
 
 				for (d = 0; d < 7; d++) {
@@ -87,13 +86,13 @@ dayofweek(int year, int month, int day, int fday)
 	return (year + year / 4 - year / 100 + year / 400 + t[month] + day) % 7;
 }
 
-static bool
+static int
 isleap(int year)
 {
 	if (year % 400 == 0)
-		return true;
+		return 1;
 	if (year % 100 == 0)
-		return false;
+		return 0;
 	return (year % 4 == 0);
 }
 
diff --git a/chmod.c b/chmod.c
index e2a56de..4b2bc32 100644
--- a/chmod.c
+++ b/chmod.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
@@ -9,7 +8,7 @@
 
 static void chmodr(const char *);
 
-static bool rflag = false;
+static int rflag = 0;
 static char *modestr = "";
 static mode_t mask = 0;
 static int ret = 0;
@@ -30,7 +29,7 @@ main(int argc, char *argv[])
 		while ((c = *++argv[0])) {
 			switch (c) {
 			case 'R':
-				rflag = true;
+				rflag = 1;
 				break;
 			case 'r': case 'w': case 'x': case 's': case 't':
 				/*
diff --git a/chown.c b/chown.c
index 906a2e8..066bd63 100644
--- a/chown.c
+++ b/chown.c
@@ -2,7 +2,6 @@
 #include <errno.h>
 #include <grp.h>
 #include <pwd.h>
-#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
@@ -11,7 +10,7 @@
 
 static void chownpwgr(const char *);
 
-static bool rflag = false;
+static int rflag = 0;
 static uid_t uid = -1;
 static gid_t gid = -1;
 static int ret = 0;
@@ -32,7 +31,7 @@ main(int argc, char *argv[])
 	ARGBEGIN {
 	case 'R':
 	case 'r':
-		rflag = true;
+		rflag = 1;
 		break;
 	default:
 		usage();
diff --git a/cmp.c b/cmp.c
index 0d7e792..c9d38f3 100644
--- a/cmp.c
+++ b/cmp.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -17,19 +16,19 @@ usage(void)
 int
 main(int argc, char *argv[])
 {
-	bool lflag = false;
-	bool sflag = false;
-	bool same = true;
+	int lflag = 0;
+	int sflag = 0;
+	int same = 1;
 	int b[2], i;
 	long line = 1, n = 1;
 	FILE *fp[2];
 
 	ARGBEGIN {
 	case 'l':
-		lflag = true;
+		lflag = 1;
 		break;
 	case 's':
-		sflag = true;
+		sflag = 1;
 		break;
 	default:
 		usage();
@@ -80,7 +79,7 @@ main(int argc, char *argv[])
 			exit(Diff);
 		} else {
 			printf("%4ld %3o %3o\n", n, b[0], b[1]);
-			same = false;
+			same = 0;
 		}
 	}
 	return same ? Same : Diff;
diff --git a/cols.c b/cols.c
index 992d31a..9262ceb 100644
--- a/cols.c
+++ b/cols.c
@@ -1,6 +1,5 @@
 /* See LICENSE file for copyright and license details. */
 #include <assert.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/comm.c b/comm.c
index 29ffbe0..1864c9f 100644
--- a/comm.c
+++ b/comm.c
@@ -1,6 +1,5 @@
 /* See LICENSE file for copyright and license details. */
 #include <limits.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/cp.c b/cp.c
index 27b2011..f1c3d9b 100644
--- a/cp.c
+++ b/cp.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdlib.h>
 #include <sys/stat.h>
 
@@ -19,26 +18,24 @@ main(int argc, char *argv[])
 
 	ARGBEGIN {
 	case 'a':
-		cp_aflag = true; /* implies -dpr */
-		cp_dflag = true;
-		cp_pflag = true;
-		cp_rflag = true;
+		/* implies -dpr */
+		cp_aflag = cp_dflag = cp_pflag = cp_rflag = 1;
 		break;
 	case 'd':
-		cp_dflag = true;
+		cp_dflag = 1;
 		break;
 	case 'p':
-		cp_pflag = true;
+		cp_pflag = 1;
 		break;
 	case 'f':
-		cp_fflag = true;
+		cp_fflag = 1;
 		break;
 	case 'R':
 	case 'r':
-		cp_rflag = true;
+		cp_rflag = 1;
 		break;
 	case 'v':
-		cp_vflag = true;
+		cp_vflag = 1;
 		break;
 	default:
 		usage();
diff --git a/cut.c b/cut.c
index 5722bc5..c20a236 100644
--- a/cut.c
+++ b/cut.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -23,8 +22,8 @@ typedef struct Range {
 static Range *list = NULL;
 static char mode = 0;
 static char delim = '\t';
-static bool nflag = false;
-static bool sflag = false;
+static int nflag = 0;
+static int sflag = 0;
 
 static void
 insert(Range *r)
@@ -164,10 +163,10 @@ main(int argc, char *argv[])
 		delim = *ARGF();
 		break;
 	case 'n':
-		nflag = true;
+		nflag = 1;
 		break;
 	case 's':
-		sflag = true;
+		sflag = 1;
 		break;
 	default:
 		usage();
diff --git a/du.c b/du.c
index b4421d0..46151ad 100644
--- a/du.c
+++ b/du.c
@@ -1,7 +1,6 @@
 /* See LICENSE file for copyright and license details. */
 #include <dirent.h>
 #include <limits.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -16,11 +15,11 @@ static char file[PATH_MAX];
 static long depth = -1;
 static long curdepth = 0;
 
-static bool aflag = false;
-static bool dflag = false;
-static bool sflag = false;
-static bool kflag = false;
-static bool hflag = false;
+static int aflag = 0;
+static int dflag = 0;
+static int sflag = 0;
+static int kflag = 0;
+static int hflag = 0;
 
 static long du(const char *);
 static void print(long n, char *path);
@@ -50,20 +49,20 @@ main(int argc, char *argv[])
 
 	ARGBEGIN {
 	case 'a':
-		aflag = true;
+		aflag = 1;
 		break;
 	case 'd':
-		dflag = true;
+		dflag = 1;
 		depth = estrtol(EARGF(usage()), 0);
 		break;
 	case 's':
-		sflag = true;
+		sflag = 1;
 		break;
 	case 'k':
-		kflag = true;
+		kflag = 1;
 		break;
 	case 'h':
-		hflag = true;
+		hflag = 1;
 		break;
 	default:
 		usage();
diff --git a/echo.c b/echo.c
index 7ba5f05..6656ac4 100644
--- a/echo.c
+++ b/echo.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -14,11 +13,11 @@ usage(void)
 int
 main(int argc, char *argv[])
 {
-	bool nflag = false;
+	int nflag = 0;
 
 	ARGBEGIN {
 	case 'n':
-		nflag = true;
+		nflag = 1;
 		break;
 	default:
 		usage();
diff --git a/expand.c b/expand.c
index 3a51e86..aa88089 100644
--- a/expand.c
+++ b/expand.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <wchar.h>
@@ -13,7 +12,7 @@ typedef struct {
 
 static int expand(Fdescr *f, int tabstop);
 
-static bool iflag = false;
+static int iflag = 0;
 
 static void
 usage(void)
@@ -30,7 +29,7 @@ main(int argc, char *argv[])
 
 	ARGBEGIN {
 	case 'i':
-		iflag = true;
+		iflag = 1;
 		break;
 	case 't':
 		tabstop = estrtol(EARGF(usage()), 0);
@@ -82,7 +81,7 @@ expand(Fdescr *dsc, int tabstop)
 {
 	int col = 0;
 	wint_t c;
-	bool bol = true;
+	int bol = 1;
 
 	for (;;) {
 		c = in(dsc);
@@ -104,18 +103,18 @@ expand(Fdescr *dsc, int tabstop)
 		case '\b':
 			if (col)
 				col--;
-			bol = false;
+			bol = 0;
 			out(c);
 			break;
 		case '\n':
 			col = 0;
-			bol = true;
+			bol = 1;
 			out(c);
 			break;
 		default:
 			col++;
 			if (c != ' ')
-				bol = false;
+				bol = 0;
 			out(c);
 			break;
 		}
diff --git a/fold.c b/fold.c
index 4f82d3a..92585af 100644
--- a/fold.c
+++ b/fold.c
@@ -1,6 +1,5 @@
 /* See LICENSE file for copyright and license details. */
 #include <ctype.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -11,8 +10,8 @@
 static void fold(FILE *, long);
 static void foldline(const char *, long);
 
-static bool bflag = false;
-static bool sflag = false;
+static int bflag = 0;
+static int sflag = 0;
 
 static void
 usage(void)
@@ -28,10 +27,10 @@ main(int argc, char *argv[])
 
 	ARGBEGIN {
 	case 'b':
-		bflag = true;
+		bflag = 1;
 		break;
 	case 's':
-		sflag = true;
+		sflag = 1;
 		break;
 	case 'w':
 		width = estrtol(EARGF(usage()), 0);
@@ -73,19 +72,19 @@ fold(FILE *fp, long width)
 static void
 foldline(const char *str, long width)
 {
-	bool space;
+	int space;
 	long col, j;
 	size_t i = 0, n = 0;
 	int c;
 
 	do {
-		space = false;
+		space = 0;
 		for (j = i, col = 0; str[j] && col <= width; j++) {
 			c = str[j];
 			if (!UTF8_POINT(c) && !bflag)
 				continue;
 			if (sflag && isspace(c)) {
-				space = true;
+				space = 1;
 				n = j+1;
 			}
 			else if (!space)
diff --git a/fs.h b/fs.h
index 2ac9574..18b7f4d 100644
--- a/fs.h
+++ b/fs.h
@@ -1,16 +1,14 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
-
-extern bool cp_aflag;
-extern bool cp_dflag;
-extern bool cp_fflag;
-extern bool cp_pflag;
-extern bool cp_rflag;
-extern bool cp_vflag;
+extern int cp_aflag;
+extern int cp_dflag;
+extern int cp_fflag;
+extern int cp_pflag;
+extern int cp_rflag;
+extern int cp_vflag;
 extern int cp_status;
 
-extern bool rm_fflag;
-extern bool rm_rflag;
+extern int rm_fflag;
+extern int rm_rflag;
 
 int cp(const char *, const char *);
 void rm(const char *);
diff --git a/grep.c b/grep.c
index 6a3951d..7352aae 100644
--- a/grep.c
+++ b/grep.c
@@ -1,6 +1,5 @@
 /* See LICENSE file for copyright and license details. */
 #include <regex.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -14,9 +13,9 @@ enum { Match = 0, NoMatch = 1, Error = 2 };
 static void addpattern(const char *);
 static int grep(FILE *, const char *);
 
-static bool eflag = false;
-static bool vflag = false;
-static bool many;
+static int eflag = 0;
+static int vflag = 0;
+static int many;
 static char mode = 0;
 
 static struct plist {
@@ -45,7 +44,7 @@ main(int argc, char *argv[])
 		break;
 	case 'e':
 		addpattern(EARGF(usage()));
-		eflag = true;
+		eflag = 1;
 		break;
 	case 'c':
 	case 'l':
@@ -57,7 +56,7 @@ main(int argc, char *argv[])
 		flags |= REG_ICASE;
 		break;
 	case 'v':
-		vflag = true;
+		vflag = 1;
 		break;
 	default:
 		usage();
diff --git a/kill.c b/kill.c
index 907eed6..04f86e2 100644
--- a/kill.c
+++ b/kill.c
@@ -2,7 +2,6 @@
 #include <ctype.h>
 #include <errno.h>
 #include <signal.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/ln.c b/ln.c
index 69e5b14..d8809ce 100644
--- a/ln.c
+++ b/ln.c
@@ -1,7 +1,6 @@
 /* See LICENSE file for copyright and license details. */
 #include <errno.h>
 #include <libgen.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -20,15 +19,15 @@ main(int argc, char *argv[])
 {
 	int (*flink)(const char *, const char *);
 	char *fname, *to;
-	bool sflag = false;
-	bool fflag = false;
+	int sflag = 0;
+	int fflag = 0;
 
 	ARGBEGIN {
 	case 'f':
-		fflag = true;
+		fflag = 1;
 		break;
 	case 's':
-		sflag = true;
+		sflag = 1;
 		break;
 	default:
 		usage();
@@ -47,7 +46,7 @@ main(int argc, char *argv[])
 
 	to = argc < 2 ? basename(argv[0]) : argv[1];
 
-	if (fflag == true)
+	if (fflag)
 		remove(to);
 	if (flink(argv[0], to) < 0)
 		eprintf("%s %s <- %s:", fname, argv[0], to);
diff --git a/ls.c b/ls.c
index e4d7b20..2af7d45 100644
--- a/ls.c
+++ b/ls.c
@@ -3,7 +3,6 @@
 #include <errno.h>
 #include <grp.h>
 #include <pwd.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -27,20 +26,20 @@ typedef struct {
 static int entcmp(const void *, const void *);
 static void ls(Entry *);
 static void lsdir(const char *);
-static void mkent(Entry *, char *, bool);
+static void mkent(Entry *, char *, int);
 static void output(Entry *);
 
-static bool aflag = false;
-static bool dflag = false;
-static bool Fflag = false;
-static bool hflag = false;
-static bool iflag = false;
-static bool lflag = false;
-static bool rflag = false;
-static bool tflag = false;
-static bool Uflag = false;
-static bool first = true;
-static bool many;
+static int aflag = 0;
+static int dflag = 0;
+static int Fflag = 0;
+static int hflag = 0;
+static int iflag = 0;
+static int lflag = 0;
+static int rflag = 0;
+static int tflag = 0;
+static int Uflag = 0;
+static int first = 1;
+static int many;
 
 static void
 usage(void)
@@ -59,31 +58,31 @@ main(int argc, char *argv[])
 		/* ignore */
 		break;
 	case 'a':
-		aflag = true;
+		aflag = 1;
 		break;
 	case 'd':
-		dflag = true;
+		dflag = 1;
 		break;
 	case 'F':
-		Fflag = true;
+		Fflag = 1;
 		break;
 	case 'h':
-		hflag = true;
+		hflag = 1;
 		break;
 	case 'i':
-		iflag = true;
+		iflag = 1;
 		break;
 	case 'l':
-		lflag = true;
+		lflag = 1;
 		break;
 	case 'r':
-		rflag = true;
+		rflag = 1;
 		break;
 	case 't':
-		tflag = true;
+		tflag = 1;
 		break;
 	case 'U':
-		Uflag = true;
+		Uflag = 1;
 		break;
 	default:
 		usage();
@@ -96,7 +95,7 @@ main(int argc, char *argv[])
 	if (!(ents = malloc(argc * sizeof *ents)))
 		eprintf("malloc:");
 	for (i = 0; i < argc; i++)
-		mkent(&ents[i], argv[i], true);
+		mkent(&ents[i], argv[i], 1);
 	qsort(ents, argc, sizeof *ents, entcmp);
 	for (i = 0; i < argc; i++)
 		ls(&ents[rflag ? argc-i-1 : i]);
@@ -145,7 +144,7 @@ lsdir(const char *path)
 		if (!first)
 			putchar('\n');
 		printf("%s:\n", path);
-		first = false;
+		first = 0;
 	}
 
 	while ((d = readdir(dp))) {
@@ -178,7 +177,7 @@ lsdir(const char *path)
 }
 
 static void
-mkent(Entry *ent, char *path, bool dostat)
+mkent(Entry *ent, char *path, int dostat)
 {
 	struct stat st;
 
diff --git a/md5sum.c b/md5sum.c
index 3f182df..0de1cb6 100644
--- a/md5sum.c
+++ b/md5sum.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
@@ -27,11 +26,11 @@ main(int argc, char *argv[])
 {
 	uint8_t md[MD5_DIGEST_LENGTH];
 	char *checkfile = NULL;
-	bool cflag = false;
+	int cflag = 0;
 
 	ARGBEGIN {
 	case 'c':
-		cflag = true;
+		cflag = 1;
 		checkfile = ARGF();
 		break;
 	default:
diff --git a/mkdir.c b/mkdir.c
index fed1bbf..ef31462 100644
--- a/mkdir.c
+++ b/mkdir.c
@@ -1,7 +1,6 @@
 /* See LICENSE file for copyright and license details. */
 #include <errno.h>
 #include <fcntl.h>
-#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
@@ -20,16 +19,16 @@ usage(void)
 int
 main(int argc, char *argv[])
 {
-	bool pflag = false;
-	bool mflag = false;
+	int pflag = 0;
+	int mflag = 0;
 	int mode;
 
 	ARGBEGIN {
 	case 'p':
-		pflag = true;
+		pflag = 1;
 		break;
 	case 'm':
-		mflag = true;
+		mflag = 1;
 		mode = estrtol(EARGF(usage()), 8);
 		break;
 	default:
diff --git a/mv.c b/mv.c
index 81f778c..e705f40 100644
--- a/mv.c
+++ b/mv.c
@@ -44,8 +44,8 @@ mv(const char *s1, const char *s2)
 	if (rename(s1, s2) == 0)
 		return 0;
 	if (errno == EXDEV) {
-		cp_rflag = true;
-		rm_rflag = true;
+		cp_rflag = 1;
+		rm_rflag = 1;
 		cp(s1, s2);
 		rm(s1);
 		return 0;
diff --git a/paste.c b/paste.c
index 997d308..918dea0 100644
--- a/paste.c
+++ b/paste.c
@@ -1,6 +1,5 @@
 /* See LICENSE file for copyright and license details. */
 #include <locale.h>
-#include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -30,7 +29,7 @@ int
 main(int argc, char *argv[])
 {
 	const char *adelim = NULL;
-	bool seq = false;
+	int seq = 0;
 	wchar_t *delim = NULL;
 	size_t len;
 	Fdescr *dsc = NULL;
@@ -40,7 +39,7 @@ main(int argc, char *argv[])
 
 	ARGBEGIN {
 	case 's':
-		seq = true;
+		seq = 1;
 		break;
 	case 'd':
 		adelim = EARGF(usage());
diff --git a/readlink.c b/readlink.c
index aa02d8f..2d6cc94 100644
--- a/readlink.c
+++ b/readlink.c
@@ -2,7 +2,6 @@
 #include <unistd.h>
 #include <errno.h>
 #include <limits.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -19,8 +18,8 @@ int
 main(int argc, char *argv[])
 {
 	char buf[PATH_MAX];
-	bool nflag = false;
-	bool fflag = false;
+	int nflag = 0;
+	int fflag = 0;
 	ssize_t n;
 
 	ARGBEGIN {
@@ -28,10 +27,10 @@ main(int argc, char *argv[])
 	case 'm':
 		eprintf("not implemented\n");
 	case 'f':
-		fflag = true;
+		fflag = 1;
 		break;
 	case 'n':
-		nflag = true;
+		nflag = 1;
 		break;
 	default:
 		usage();
diff --git a/renice.c b/renice.c
index cca6954..78ba233 100644
--- a/renice.c
+++ b/renice.c
@@ -1,17 +1,16 @@
 /* See LICENSE file for copyright and license details. */
-#include <sys/resource.h>
 #include <errno.h>
 #include <limits.h>
 #include <pwd.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/resource.h>
 
 #include "util.h"
 
 static int strtop(const char *);
-static bool renice(int, int, long);
+static int renice(int, int, long);
 
 static void
 usage(void)
@@ -95,7 +94,7 @@ strtop(const char *s)
 	return (int)n;
 }
 
-static bool
+static int
 renice(int which, int who, long adj)
 {
 	errno = 0;
@@ -103,15 +102,15 @@ renice(int which, int who, long adj)
 	if (errno != 0) {
 		fprintf(stderr, "can't get %d nice level: %s\n",
 		        who, strerror(errno));
-		return false;
+		return 0;
 	}
 
 	adj = MAX(-NZERO, MIN(adj, NZERO - 1));
 	if (setpriority(which, who, (int)adj) == -1) {
 		fprintf(stderr, "can't set %d nice level: %s\n",
 		        who, strerror(errno));
-		return false;
+		return 0;
 	}
 
-	return true;
+	return 1;
 }
diff --git a/rm.c b/rm.c
index 33958c1..a27dcb4 100644
--- a/rm.c
+++ b/rm.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -19,18 +18,18 @@ main(int argc, char *argv[])
 {
 	ARGBEGIN {
 	case 'f':
-		rm_fflag = true;
+		rm_fflag = 1;
 		break;
 	case 'R':
 	case 'r':
-		rm_rflag = true;
+		rm_rflag = 1;
 		break;
 	default:
 		usage();
 	} ARGEND;
 
 	if (argc < 1) {
-		if (rm_fflag == false)
+		if (!rm_fflag)
 			usage();
 		else
 			return 0;
diff --git a/seq.c b/seq.c
index e165b2b..bff3af6 100644
--- a/seq.c
+++ b/seq.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -9,7 +8,7 @@
 
 static int digitsleft(const char *);
 static int digitsright(const char *);
-static bool validfmt(const char *);
+static int validfmt(const char *);
 
 static void
 usage(void)
@@ -22,7 +21,7 @@ int
 main(int argc, char *argv[])
 {
 	const char *starts = "1", *steps = "1", *ends = "1", *sep = "\n";
-	bool wflag = false;
+	int wflag = 0;
 	char *tmp, ftmp[BUFSIZ], *fmt = ftmp;
 	double start, step, end, out, dir;
 	int left, right;
@@ -37,7 +36,7 @@ main(int argc, char *argv[])
 		sep = EARGF(usage());
 		break;
 	case 'w':
-		wflag = true;
+		wflag = 1;
 		break;
 	default:
 		usage();
@@ -116,7 +115,7 @@ digitsright(const char *d)
 	return MAX(0, after - shift);
 }
 
-static bool
+static int
 validfmt(const char *fmt)
 {
 	int occur = 0;
@@ -149,6 +148,6 @@ format:
 		occur++;
 		goto literal;
 	default:
-		return false;
+		return 0;
 	}
 }
diff --git a/sha1sum.c b/sha1sum.c
index f6f9cf2..3438c7f 100644
--- a/sha1sum.c
+++ b/sha1sum.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -27,11 +26,11 @@ main(int argc, char *argv[])
 {
 	uint8_t md[SHA1_DIGEST_LENGTH];
 	char *checkfile = NULL;
-	bool cflag = false;
+	int cflag = 0;
 
 	ARGBEGIN {
 	case 'c':
-		cflag = true;
+		cflag = 1;
 		checkfile = ARGF();
 		break;
 	default:
diff --git a/sha256sum.c b/sha256sum.c
index 943de2b..aa642a4 100644
--- a/sha256sum.c
+++ b/sha256sum.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -27,11 +26,11 @@ main(int argc, char *argv[])
 {
 	uint8_t md[SHA256_DIGEST_LENGTH];
 	char *checkfile = NULL;
-	bool cflag = false;
+	int cflag = 0;
 
 	ARGBEGIN {
 	case 'c':
-		cflag = true;
+		cflag = 1;
 		checkfile = ARGF();
 		break;
 	default:
diff --git a/sha512sum.c b/sha512sum.c
index 83a5f27..ca835e8 100644
--- a/sha512sum.c
+++ b/sha512sum.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -27,11 +26,11 @@ main(int argc, char *argv[])
 {
 	uint8_t md[SHA512_DIGEST_LENGTH];
 	char *checkfile = NULL;
-	bool cflag = false;
+	int cflag = 0;
 
 	ARGBEGIN {
 	case 'c':
-		cflag = true;
+		cflag = 1;
 		checkfile = ARGF();
 		break;
 	default:
diff --git a/sort.c b/sort.c
index 3da9ccf..5513442 100644
--- a/sort.c
+++ b/sort.c
@@ -1,6 +1,5 @@
 /* See LICENSE file for copyright and license details. */
 #include <ctype.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -41,7 +40,7 @@ static int parse_keydef(struct keydef *, char *, int);
 static char *nextcol(char *);
 static char *columns(char *, const struct keydef *);
 
-static bool uflag = false;
+static int uflag = 0;
 static char *fieldsep = NULL;
 
 static void
@@ -77,7 +76,7 @@ main(int argc, char *argv[])
 			usage();
 		break;
 	case 'u':
-		uflag = true;
+		uflag = 1;
 		break;
 	default:
 		usage();
diff --git a/tar.c b/tar.c
index 81634c1..65898d5 100644
--- a/tar.c
+++ b/tar.c
@@ -2,7 +2,6 @@
 #include <grp.h>
 #include <limits.h>
 #include <pwd.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -53,7 +52,7 @@ static FILE *tarfile;
 static ino_t tarinode;
 static dev_t tardev;
 
-static bool mflag = false;
+static int mflag = 0;
 
 static void
 usage(void)
@@ -86,7 +85,7 @@ main(int argc, char *argv[])
 		file = EARGF(usage());
 		break;
 	case 'm':
-		mflag = true;
+		mflag = 1;
 		break;
 	default:
 		usage();
@@ -118,7 +117,7 @@ main(int argc, char *argv[])
 				dir = argv[0];
 				break;
 			case 'm':
-				mflag = true;
+				mflag = 1;
 				break;
 			default:
 				usage();
diff --git a/tee.c b/tee.c
index 1c356aa..638e59f 100644
--- a/tee.c
+++ b/tee.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -15,7 +14,7 @@ usage(void)
 int
 main(int argc, char *argv[])
 {
-	bool aflag = false;
+	int aflag = 0;
 	char buf[BUFSIZ];
 	int i, nfps;
 	size_t n;
@@ -23,7 +22,7 @@ main(int argc, char *argv[])
 
 	ARGBEGIN {
 	case 'a':
-		aflag = true;
+		aflag = 1;
 		break;
 	default:
 		usage();
diff --git a/test.c b/test.c
index 0d771ef..ad2ca7d 100644
--- a/test.c
+++ b/test.c
@@ -1,6 +1,5 @@
 /* See LICENSE file for copyright and license details. */
 #include <errno.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -19,40 +18,40 @@ stoi(char *s, int *a)
 		enprintf(2, "bad integer %s\n", s);
 }
 
-static bool unary_b(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISBLK  (buf.st_mode); }
-static bool unary_c(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISCHR  (buf.st_mode); }
-static bool unary_d(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISDIR  (buf.st_mode); }
-static bool unary_f(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISREG  (buf.st_mode); }
-static bool unary_g(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISGID & buf.st_mode ; }
-static bool unary_h(char *s) { struct stat buf; if (lstat(s, &buf)) return 0; return S_ISLNK  (buf.st_mode); }
-static bool unary_p(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISFIFO (buf.st_mode); }
-static bool unary_S(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISSOCK (buf.st_mode); }
-static bool unary_s(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return           buf.st_size ; }
-static bool unary_u(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISUID & buf.st_mode ; }
+static int unary_b(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISBLK  (buf.st_mode); }
+static int unary_c(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISCHR  (buf.st_mode); }
+static int unary_d(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISDIR  (buf.st_mode); }
+static int unary_f(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISREG  (buf.st_mode); }
+static int unary_g(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISGID & buf.st_mode ; }
+static int unary_h(char *s) { struct stat buf; if (lstat(s, &buf)) return 0; return S_ISLNK  (buf.st_mode); }
+static int unary_p(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISFIFO (buf.st_mode); }
+static int unary_S(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISSOCK (buf.st_mode); }
+static int unary_s(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return           buf.st_size ; }
+static int unary_u(char *s) { struct stat buf; if ( stat(s, &buf)) return 0; return S_ISUID & buf.st_mode ; }
 
-static bool unary_n(char *s) { return  strlen(s); }
-static bool unary_z(char *s) { return !strlen(s); }
+static int unary_n(char *s) { return  strlen(s); }
+static int unary_z(char *s) { return !strlen(s); }
 
-static bool unary_e(char *s) { return access(s, F_OK); }
-static bool unary_r(char *s) { return access(s, R_OK); }
-static bool unary_w(char *s) { return access(s, W_OK); }
-static bool unary_x(char *s) { return access(s, X_OK); }
+static int unary_e(char *s) { return access(s, F_OK); }
+static int unary_r(char *s) { return access(s, R_OK); }
+static int unary_w(char *s) { return access(s, W_OK); }
+static int unary_x(char *s) { return access(s, X_OK); }
 
-static bool unary_t(char *s) { int fd; stoi(s, &fd); return isatty(fd); }
+static int unary_t(char *s) { int fd; stoi(s, &fd); return isatty(fd); }
 
-static bool binary_se(char *s1, char *s2) { return strcmp(s1, s2) == 0; }
-static bool binary_sn(char *s1, char *s2) { return strcmp(s1, s2) != 0; }
+static int binary_se(char *s1, char *s2) { return strcmp(s1, s2) == 0; }
+static int binary_sn(char *s1, char *s2) { return strcmp(s1, s2) != 0; }
 
-static bool binary_eq(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a == b; }
-static bool binary_ne(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a != b; }
-static bool binary_gt(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a >  b; }
-static bool binary_ge(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a >= b; }
-static bool binary_lt(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a <  b; }
-static bool binary_le(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a <= b; }
+static int binary_eq(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a == b; }
+static int binary_ne(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a != b; }
+static int binary_gt(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a >  b; }
+static int binary_ge(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a >= b; }
+static int binary_lt(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a <  b; }
+static int binary_le(char *s1, char *s2) { int a, b; stoi(s1, &a); stoi(s2, &b); return a <= b; }
 
 typedef struct {
 	char *name;
-	bool (*func)();
+	int (*func)();
 } Test;
 
 static Test unary[] = {
@@ -102,19 +101,19 @@ find_test(Test *tests, char *name)
 	return NULL;
 }
 
-static bool
+static int
 noarg(char **argv)
 {
 	return 0;
 }
 
-static bool
+static int
 onearg(char **argv)
 {
 	return strlen(argv[0]);
 }
 
-static bool
+static int
 twoarg(char **argv)
 {
 	Test *t = find_test(unary, *argv);
@@ -128,7 +127,7 @@ twoarg(char **argv)
 	return enprintf(2, "bad unary test %s\n", argv[0]), 0;
 }
 
-static bool
+static int
 threearg(char **argv)
 {
 	Test *t = find_test(binary, argv[1]);
@@ -142,7 +141,7 @@ threearg(char **argv)
 	return enprintf(2, "bad binary test %s\n", argv[1]), 0;
 }
 
-static bool
+static int
 fourarg(char **argv)
 {
 	if (strcmp(argv[0], "!") == 0)
@@ -154,7 +153,7 @@ fourarg(char **argv)
 int
 main(int argc, char **argv)
 {
-	bool (*narg[])(char**) = { noarg, onearg, twoarg, threearg, fourarg };
+	int (*narg[])(char**) = { noarg, onearg, twoarg, threearg, fourarg };
 	int len = strlen(argv[0]);
 
 	if (len && argv[0][len - 1] == '[')
diff --git a/touch.c b/touch.c
index 0884ee9..90fa7db 100644
--- a/touch.c
+++ b/touch.c
@@ -1,7 +1,6 @@
 /* See LICENSE file for copyright and license details. */
 #include <errno.h>
 #include <fcntl.h>
-#include <stdbool.h>
 #include <stdlib.h>
 #include <sys/stat.h>
 #include <time.h>
@@ -12,7 +11,7 @@
 
 static void touch(const char *);
 
-static bool cflag = false;
+static int cflag = 0;
 static time_t t;
 
 static void
@@ -28,7 +27,7 @@ main(int argc, char *argv[])
 
 	ARGBEGIN {
 	case 'c':
-		cflag = true;
+		cflag = 1;
 		break;
 	case 't':
 		t = estrtol(EARGF(usage()), 0);
diff --git a/tr.c b/tr.c
index 3c047fb..19598d3 100644
--- a/tr.c
+++ b/tr.c
@@ -1,6 +1,5 @@
 /* See LICENSE file for copyright and license details. */
 #include <locale.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/uname.c b/uname.c
index 12cff59..400ba2e 100644
--- a/uname.c
+++ b/uname.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/utsname.h>
@@ -16,36 +15,36 @@ usage(void)
 int
 main(int argc, char *argv[])
 {
-	bool mflag = false;
-	bool nflag = false;
-	bool rflag = false;
-	bool sflag = false;
-	bool vflag = false;
+	int mflag = 0;
+	int nflag = 0;
+	int rflag = 0;
+	int sflag = 0;
+	int vflag = 0;
 	struct utsname u;
 
 	ARGBEGIN {
 	case 'a':
-		mflag = nflag = rflag = sflag = vflag = true;
+		mflag = nflag = rflag = sflag = vflag = 1;
 		break;
 	case 'm':
-		mflag = true;
+		mflag = 1;
 		break;
 	case 'n':
-		nflag = true;
+		nflag = 1;
 		break;
 	case 'r':
-		rflag = true;
+		rflag = 1;
 		break;
 	case 's':
-		sflag = true;
+		sflag = 1;
 		break;
 	case 'v':
-		vflag = true;
+		vflag = 1;
 		break;
 	default:
 		usage();
 	} ARGEND;
-	if (uname(&u) == -1)
+	if (uname(&u) < 0)
 		eprintf("uname:");
 
 	if (sflag || !(nflag || rflag || vflag || mflag))
diff --git a/unexpand.c b/unexpand.c
index 30ff57f..ecf6ba3 100644
--- a/unexpand.c
+++ b/unexpand.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <wchar.h>
@@ -13,7 +12,7 @@ typedef struct {
 
 static void unexpand(Fdescr *dsc);
 
-static bool aflag = false;
+static int aflag = 0;
 static int tabsize = 8;
 
 static void
@@ -35,7 +34,7 @@ main(int argc, char *argv[])
 			eprintf("unexpand: invalid tabsize\n", argv[0]);
 		/* Fallthrough: -t implies -a */
 	case 'a':
-		aflag = true;
+		aflag = 1;
 		break;
 	default:
 		usage();
@@ -98,7 +97,7 @@ static void
 unexpand(Fdescr *dsc)
 {
 	unsigned int n = 0, col = 0;
-	bool bol = true;
+	int bol = 1;
 	wint_t c;
 
 	while ((c = in(dsc)) != EOF) {
@@ -118,20 +117,20 @@ unexpand(Fdescr *dsc)
 				unexpandspan(n, col);
 			col -= (col > 0);
 			n = 0;
-			bol = false;
+			bol = 0;
 			break;
 		case '\n':
 			if (bol || aflag)
 				unexpandspan(n, col);
 			n = col = 0;
-			bol = true;
+			bol = 1;
 			break;
 		default:
 			if (bol || aflag)
 				unexpandspan(n, col);
 			n = 0;
 			col++;
-			bol = false;
+			bol = 0;
 		}
 		if ((c != ' ' && c != '\t') || (!aflag && !bol))
 			out(c);
diff --git a/uniq.c b/uniq.c
index a9bbf99..7d4caba 100644
--- a/uniq.c
+++ b/uniq.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -13,8 +12,8 @@ static void uniq(FILE *, const char *);
 static void uniqfinish(void);
 
 static const char *countfmt = "";
-static bool dflag = false;
-static bool uflag = false;
+static int dflag = 0;
+static int uflag = 0;
 
 static char *prevline = NULL;
 static long prevlinecount = 0;
@@ -37,10 +36,10 @@ main(int argc, char *argv[])
 		countfmt = "%7ld ";
 		break;
 	case 'd':
-		dflag = true;
+		dflag = 1;
 		break;
 	case 'u':
-		uflag = true;
+		uflag = 1;
 		break;
 	default:
 		usage();
@@ -63,7 +62,7 @@ main(int argc, char *argv[])
 static void
 uniqline(char *l)
 {
-	bool linesequel = ((l == NULL) || (prevline == NULL))
+	int linesequel = ((l == NULL) || (prevline == NULL))
 		? l == prevline
 		: !strcmp(l, prevline);
 
diff --git a/util/cp.c b/util/cp.c
index be80a61..a5c3816 100644
--- a/util/cp.c
+++ b/util/cp.c
@@ -3,7 +3,6 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -16,12 +15,12 @@
 #include "../text.h"
 #include "../util.h"
 
-bool cp_aflag = false;
-bool cp_dflag = false;
-bool cp_fflag = false;
-bool cp_pflag = false;
-bool cp_rflag = false;
-bool cp_vflag = false;
+int cp_aflag = 0;
+int cp_dflag = 0;
+int cp_fflag = 0;
+int cp_pflag = 0;
+int cp_rflag = 0;
+int cp_vflag = 0;
 int cp_status = 0;
 
 int
@@ -40,15 +39,15 @@ cp(const char *s1, const char *s2)
 	if (cp_vflag)
 		printf("'%s' -> '%s'\n", s1, s2);
 
-	if (cp_dflag == true)
+	if (cp_dflag)
 		r = lstat(s1, &st);
 	else
 		r = stat(s1, &st);
 
 	if (r == 0) {
-		if (cp_dflag == true && S_ISLNK(st.st_mode)) {
+		if (cp_dflag && S_ISLNK(st.st_mode)) {
 			if (readlink(s1, buf, sizeof(buf) - 1) >= 0) {
-				if (cp_fflag == true);
+				if (cp_fflag);
 					unlink(s2);
 				if (symlink(buf, s2) != 0) {
 					weprintf("%s: can't create '%s'\n", argv0, s2);
@@ -92,7 +91,7 @@ cp(const char *s1, const char *s2)
 		}
 	}
 
-	if (cp_aflag == true) {
+	if (cp_aflag) {
 		if (S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode) ||
 		   S_ISSOCK(st.st_mode) || S_ISFIFO(st.st_mode)) {
 			unlink(s2);
@@ -112,7 +111,7 @@ cp(const char *s1, const char *s2)
 	}
 
 	if (!(f2 = fopen(s2, "w"))) {
-		if (cp_fflag == true) {
+		if (cp_fflag) {
 			unlink(s2);
 			if (!(f2 = fopen(s2, "w"))) {
 				weprintf("fopen %s:", s2);
@@ -131,7 +130,7 @@ cp(const char *s1, const char *s2)
 	fclose(f1);
 
 preserve:
-	if (cp_aflag == true || cp_pflag == true) {
+	if (cp_aflag || cp_pflag) {
 		if (!(S_ISLNK(st.st_mode))) {
 			/* timestamp */
 			ut.actime = st.st_atime;
diff --git a/util/putword.c b/util/putword.c
index b5f3973..c460703 100644
--- a/util/putword.c
+++ b/util/putword.c
@@ -1,5 +1,4 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 
 #include "../util.h"
@@ -7,11 +6,11 @@
 void
 putword(const char *s)
 {
-	static bool first = true;
+	static int first = 1;
 
 	if (!first)
 		putchar(' ');
 
 	fputs(s, stdout);
-	first = false;
+	first = 0;
 }
diff --git a/util/rm.c b/util/rm.c
index ea84fa2..a89b11c 100644
--- a/util/rm.c
+++ b/util/rm.c
@@ -1,11 +1,11 @@
 /* See LICENSE file for copyright and license details. */
-#include <stdbool.h>
 #include <stdio.h>
 
 #include "../fs.h"
 #include "../util.h"
 
-bool rm_fflag = false, rm_rflag = false;
+int rm_fflag = 0;
+int rm_rflag = 0;
 
 void
 rm(const char *path)
diff --git a/wc.c b/wc.c
index 2eb63ee..f2a7206 100644
--- a/wc.c
+++ b/wc.c
@@ -1,6 +1,5 @@
 /* See LICENSE file for copyright and license details. */
 #include <ctype.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -10,8 +9,8 @@
 static void output(const char *, long, long, long);
 static void wc(FILE *, const char *);
 
-static bool lflag = false;
-static bool wflag = false;
+static int lflag = 0;
+static int wflag = 0;
 static char cmode = 0;
 static long tc = 0, tl = 0, tw = 0;
 
@@ -35,10 +34,10 @@ main(int argc, char *argv[])
 		cmode = 'm';
 		break;
 	case 'l':
-		lflag = true;
+		lflag = 1;
 		break;
 	case 'w':
-		wflag = true;
+		wflag = 1;
 		break;
 	default:
 		usage();
@@ -64,7 +63,7 @@ main(int argc, char *argv[])
 void
 output(const char *str, long nc, long nl, long nw)
 {
-	bool noflags = !cmode && !lflag && !wflag;
+	int noflags = !cmode && !lflag && !wflag;
 
 	if (lflag || noflags)
 		printf(" %5ld", nl);
@@ -80,7 +79,7 @@ output(const char *str, long nc, long nl, long nw)
 void
 wc(FILE *fp, const char *str)
 {
-	bool word = false;
+	int word = 0;
 	int c;
 	long nc = 0, nl = 0, nw = 0;
 
@@ -90,9 +89,9 @@ wc(FILE *fp, const char *str)
 		if (c == '\n')
 			nl++;
 		if (!isspace(c))
-			word = true;
+			word = 1;
 		else if (word) {
-			word = false;
+			word = 0;
 			nw++;
 		}
 	}