diff --git a/Source/NSString.m b/Source/NSString.m
index fb95101f3..3af1d3b63 100644
--- a/Source/NSString.m
+++ b/Source/NSString.m
@@ -5580,6 +5580,7 @@ static NSFileManager *fm = nil;
  */
 - (NSComparisonResult) caseInsensitiveCompare: (NSString*)aString
 {
+  if (string == self) return NSOrderedSame;
   return [self compare: aString
 	       options: NSCaseInsensitiveSearch
 		 range: ((NSRange){0, [self length]})];