diff -ur dash-0.5.9.1.orig/src/mystring.c dash-0.5.9.1/src/mystring.c
--- dash-0.5.9.1.orig/src/mystring.c	2017-02-28 04:37:45.000000000 +0100
+++ dash-0.5.9.1/src/mystring.c	2017-02-28 04:31:39.000000000 +0100
@@ -213,7 +213,7 @@
 single_quote(const char *s, int conditional) {
 	char *p;
 
-	if (conditional && s[strspn(s, SHELLSAFECHARS)] == '\0' && ! is_kwd(s))
+	if (conditional && *s != '\0' && s[strspn(s, SHELLSAFECHARS)] == '\0' && ! is_kwd(s))
 		return (char *)s;
 
 	STARTSTACKSTR(p);