diff --git a/skeletons/GeneralizedTime.c b/skeletons/GeneralizedTime.c
index aabe66d..6934a82 100644
--- a/skeletons/GeneralizedTime.c
+++ b/skeletons/GeneralizedTime.c
@@ -326,7 +326,7 @@
 #undef	B2T
 #define	B2F(var)	do {					\
 		unsigned ch = *buf;				\
-		if(ch < 0x30 && ch > 0x39) {			\
+		if(ch < 0x30 || ch > 0x39) {			\
 			errno = EINVAL;				\
 			return -1;				\
 		} else {					\