diff --git a/racket/src/rktio/rktio_time.c b/racket/src/rktio/rktio_time.c
index 0fc6c299cd..4ba8b64d6e 100644
--- a/racket/src/rktio/rktio_time.c
+++ b/racket/src/rktio/rktio_time.c
@@ -373,9 +373,9 @@ rktio_date_t *rktio_seconds_to_date(rktio_t *rktio, rktio_timestamp_t seconds, i
     }
 #else
     if (get_gmt)
-      success = gmtime_r(&now, &localTime);
+      success = (gmtime_r(&now, &localTime) != NULL);
     else
-      success = localtime_r(&now, &localTime);
+      success = (localtime_r(&now, &localTime) != NULL);
 #endif
 
     if (success) {