diff --git a/libbb/skip_whitespace.c b/libbb/skip_whitespace.c
index e85f385..7b12326 100644
--- a/libbb/skip_whitespace.c
+++ b/libbb/skip_whitespace.c
@@ -11,15 +11,22 @@
 
 char* FAST_FUNC skip_whitespace(const char *s)
 {
-	/* NB: isspace('\0') returns 0 */
-	while (isspace(*s)) ++s;
+	/* In POSIX/C locale (the only locale we care about: do we REALLY want
+	 * to allow Unicode whitespace in, say, .conf files? nuts!)
+	 * isspace is only these chars: "\t\n\v\f\r" and space.
+	 * "\t\n\v\f\r" happen to have ASCII codes 9,10,11,12,13.
+	 * Use that.
+	 */
+	while (*s == ' ' || (unsigned char)(*s - 9) <= (13 - 9))
+		s++;
 
 	return (char *) s;
 }
 
 char* FAST_FUNC skip_non_whitespace(const char *s)
 {
-	while (*s && !isspace(*s)) ++s;
+	while (*s != '\0' && *s != ' ' && (unsigned char)(*s - 9) > (13 - 9))
+		s++;
 
 	return (char *) s;
 }