diff --git a/stagit-index.c b/stagit-index.c
index e2cac59..5875d21 100644
--- a/stagit-index.c
+++ b/stagit-index.c
@@ -49,7 +49,8 @@ printtimeformat(FILE *fp, const git_time *intime, const char *fmt)
 	char out[32];
 
 	t = (time_t) intime->time + (intime->offset * 60);
-	intm = gmtime(&t);
+	if (!(intm = gmtime(&t)))
+		return;
 	strftime(out, sizeof(out), fmt, intm);
 	fputs(out, fp);
 }
diff --git a/stagit.c b/stagit.c
index cbb0a77..e4e4cfe 100644
--- a/stagit.c
+++ b/stagit.c
@@ -190,7 +190,8 @@ printtimeformat(FILE *fp, const git_time *intime, const char *fmt)
 	char out[32];
 
 	t = (time_t) intime->time + (intime->offset * 60);
-	intm = gmtime(&t);
+	if (!(intm = gmtime(&t)))
+		return;
 	strftime(out, sizeof(out), fmt, intm);
 	fputs(out, fp);
 }