diff --git a/AppKit/CPTextView/CPTextView.j b/AppKit/CPTextView/CPTextView.j
index 2b5dd04d7..b2f646611 100755
--- a/AppKit/CPTextView/CPTextView.j
+++ b/AppKit/CPTextView/CPTextView.j
@@ -429,6 +429,10 @@ var kDelegateRespondsTo_textShouldBeginEditing
 
 - (void)_replaceCharactersInRange:aRange withAttributedString:(CPString)aString
 {
+    [[[[self window] undoManager] prepareWithInvocationTarget:self]
+                _replaceCharactersInRange:CPMakeRange(aRange.location, [aString length])
+                     withAttributedString:[_textStorage attributedSubstringFromRange:CPMakeRangeCopy(aRange)]];
+
     [_textStorage replaceCharactersInRange:aRange withAttributedString:aString];
     [self setSelectedRange:CPMakeRange(aRange.location, [aString length])];
     [_layoutManager _validateLayoutAndGlyphs];
@@ -439,6 +443,10 @@ var kDelegateRespondsTo_textShouldBeginEditing
 }
 - (void)_replaceCharactersInRange:(CPRange)aRange withString:(CPString)aString
 {
+    [[[[self window] undoManager] prepareWithInvocationTarget:self]
+                _replaceCharactersInRange:CPMakeRange(aRange.location, [aString length])
+                               withString:[[self string] substringWithRange:CPMakeRangeCopy(aRange)]];
+
     [_textStorage replaceCharactersInRange:CPMakeRangeCopy(aRange) withString:aString];
     [self setSelectedRange:CPMakeRange(aRange.location, aString.length)];
     [_layoutManager _validateLayoutAndGlyphs];