diff --git a/contrib/pg_upgrade/util.c b/contrib/pg_upgrade/util.c
index 3f3a4c700d07240cfc813eaf37d0f5c88b1edb40..edd3a45bc9fe1c41a06bf80e058d256229ea402b 100644
--- a/contrib/pg_upgrade/util.c
+++ b/contrib/pg_upgrade/util.c
@@ -269,5 +269,5 @@ getErrorText(int errNum)
 unsigned int
 str2uint(const char *str)
 {
-	return strtol(str, NULL, 10);
+	return strtoul(str, NULL, 10);
 }