diff --git a/src/diff/children.js b/src/diff/children.js
index f8807eea7c..57b4d0b424 100644
--- a/src/diff/children.js
+++ b/src/diff/children.js
@@ -153,7 +153,8 @@ export function diffChildren(
 				firstChildDom = newDom;
 			}
 
-			let isMounting = oldVNode === EMPTY_OBJ || oldVNode._original === null;
+			let isMounting =
+				isHydrating || oldVNode === EMPTY_OBJ || oldVNode._original === null;
 			let hasMatchingIndex = !isMounting && matchingIndex === skewedIndex;
 			if (isMounting) {
 				if (matchingIndex == -1) {
@@ -187,7 +188,6 @@ export function diffChildren(
 				hasMatchingIndex || (matchingIndex == i && !isMounting);
 
 			if (
-				!isHydrating &&
 				!isMounting &&
 				typeof childVNode.type == 'function' &&
 				(matchingIndex !== skewedIndex ||