--- a/widget/cocoa/TextInputHandler.mm
+++ b/widget/cocoa/TextInputHandler.mm
@@ -2803,24 +2803,31 @@ IMEInputHandler::GetRangeCount(NSAttribu
 }
 
 already_AddRefed<mozilla::TextRangeArray>
 IMEInputHandler::CreateTextRangeArray(NSAttributedString *aAttrString,
                                       NSRange& aSelectedRange)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NIL;
 
+  RefPtr<mozilla::TextRangeArray> textRangeArray =
+                                      new mozilla::TextRangeArray();
+
+  // Note that we shouldn't append ranges when composition string
+  // is empty because it may cause TextComposition confused.
+  if (![aAttrString length]) {
+    return textRangeArray.forget();
+  }
+
   // Convert the Cocoa range into the TextRange Array used in Gecko.
   // Iterate through the attributed string and map the underline attribute to
   // Gecko IME textrange attributes.  We may need to change the code here if
   // we change the implementation of validAttributesForMarkedText.
   NSRange limitRange = NSMakeRange(0, [aAttrString length]);
   uint32_t rangeCount = GetRangeCount(aAttrString);
-  RefPtr<mozilla::TextRangeArray> textRangeArray =
-                                      new mozilla::TextRangeArray();
   for (uint32_t i = 0; i < rangeCount && limitRange.length > 0; i++) {
     NSRange effectiveRange;
     id attributeValue = [aAttrString attribute:NSUnderlineStyleAttributeName
                                        atIndex:limitRange.location
                          longestEffectiveRange:&effectiveRange
                                        inRange:limitRange];
 
     TextRange range;