diff --git a/sup b/sup
index c4c544c..3b0f832 100755
--- a/sup
+++ b/sup
@@ -47,7 +47,7 @@ sup.mktemp() {
 }
 
 sup.scrot() {
-	local tmp_file_name
+	local tmp_file
 
 	[[ "$scrot_exec" ]] || { scrot_exec=`which scrot`; }
 	[[ "$scrot_exec" ]] || {
@@ -58,14 +58,14 @@ sup.scrot() {
 	[[ "$flag_scrot_fullscreen" ]] || { scrot_args+=( '-s' ); }
 	[[ "$cfg_scrot_delay" ]] && { scrot_args+=( "-d $cfg_scrot_delay" ); }
 
-	tmp_file_name="$(sup.mktemp "${cfg_tmp_dir}" "${cfg_screenshot_ext}")"
+	tmp_file="$(sup.mktemp "${cfg_tmp_dir}" ".${cfg_screenshot_ext}")"
 
-	scrot "${scrot_args[@]}" "${cfg_tmp_dir}/$tmp_file_name" || {
+	scrot "${scrot_args[@]}" "$tmp_file" || {
 		sup.err "Failed to take a screenshot."
 		return 1
 	}
 
-	echo "${cfg_tmp_dir}/$tmp_file_name"
+	echo "$tmp_file"
 }
 
 sup.exclude() {