Index: lib/libc/stdtime/strptime.c
===================================================================
--- lib/libc/stdtime/strptime.c
+++ lib/libc/stdtime/strptime.c
@@ -293,6 +293,10 @@
 					return (NULL);
 			} else if (i > 12)
 				return (NULL);
+			if (c == 'I' || c == 'l') {
+				if (i == 0)
+					return (NULL);
+			}
 
 			tm->tm_hour = i;