diff --git a/lang/cem/libcc/gen/localtime.c b/lang/cem/libcc/gen/localtime.c
index 8f469d836..b931ee3ff 100644
--- a/lang/cem/libcc/gen/localtime.c
+++ b/lang/cem/libcc/gen/localtime.c
@@ -16,6 +16,8 @@ last_sunday(d, t)
 	return d - (d - first) % 7;
 }
 
+extern struct tm *gmtime();
+
 struct tm *
 localtime(clock)
 	long *clock;