diff --git a/moment-timezone.js b/moment-timezone.js
index dd2f0213..6e568cd2 100644
--- a/moment-timezone.js
+++ b/moment-timezone.js
@@ -640,7 +640,7 @@
 			offset;
 
 		if (mom._z === undefined) {
-			if (zone && needsOffset(mom) && !mom._isUTC) {
+			if (zone && needsOffset(mom) && !mom._isUTC && mom.isValid()) {
 				mom._d = moment.utc(mom._a)._d;
 				mom.utc().add(zone.parse(mom), 'minutes');
 			}