diff --git a/External/diffmatchpatch/DiffMatchPatch.m b/External/diffmatchpatch/DiffMatchPatch.m
index 4a88987c..c6cb52df 100644
--- a/External/diffmatchpatch/DiffMatchPatch.m
+++ b/External/diffmatchpatch/DiffMatchPatch.m
@@ -190,7 +190,7 @@ - (id)copyWithZone:(NSZone *)zone
 {
   Patch *newPatch = [[[self class] allocWithZone:zone] init];
 
-  newPatch.diffs = [[NSMutableArray alloc] initWithArray:self.diffs copyItems:YES];
+  newPatch.diffs = [[[NSMutableArray alloc] initWithArray:self.diffs copyItems:YES] autorelease];
   newPatch.start1 = self.start1;
   newPatch.start2 = self.start2;
   newPatch.length1 = self.length1;