diff --git a/intl/unicharutil/util/nsUnicodeProperties.cpp b/intl/unicharutil/util/nsUnicodeProperties.cpp
index 8a2b04a8b0..e78725b036 100644
--- a/intl/unicharutil/util/nsUnicodeProperties.cpp
+++ b/intl/unicharutil/util/nsUnicodeProperties.cpp
@@ -153,7 +153,9 @@ IsClusterExtender(uint32_t aCh, uint8_t aCategory)
     return ((aCategory >= HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK &&
              aCategory <= HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) ||
             (aCh >= 0x200c && aCh <= 0x200d) || // ZWJ, ZWNJ
-            (aCh >= 0xff9e && aCh <= 0xff9f));  // katakana sound marks
+            (aCh >= 0xff9e && aCh <= 0xff9f) || // katakana sound marks
+            (aCh >= 0x1F3FB && aCh <= 0x1F3FF) || // fitzpatrick skin tone modifiers
+            (aCh >= 0xe0020 && aCh <= 0xe007f)); // emoji (flag) tag characters
 }
 
 enum HSType {
@@ -224,8 +226,25 @@ ClusterIterator::Next()
         }
     }
 
+    const uint32_t kVS16 = 0xfe0f;
+    const uint32_t kZWJ = 0x200d;
+    // UTF-16 surrogate values for Fitzpatrick type modifiers
+    const uint32_t kFitzpatrickHigh = 0xD83C;
+    const uint32_t kFitzpatrickLowFirst = 0xDFFB;
+    const uint32_t kFitzpatrickLowLast = 0xDFFF;
+
+    bool baseIsEmoji = (GetEmojiPresentation(ch) == EmojiDefault) ||
+                       (GetEmojiPresentation(ch) == TextDefault &&
+                        ((mPos < mLimit && *mPos == kVS16) ||
+                         (mPos + 1 < mLimit &&
+                          *mPos == kFitzpatrickHigh &&
+                          *(mPos + 1) >= kFitzpatrickLowFirst &&
+                          *(mPos + 1) <= kFitzpatrickLowLast)));
+    bool prevWasZwj = false;
+
     while (mPos < mLimit) {
         ch = *mPos;
+        size_t chLen = 1;
 
         // Check for surrogate pairs; note that isolated surrogates will just
         // be treated as generic (non-cluster-extending) characters here,
@@ -233,16 +252,21 @@ ClusterIterator::Next()
         if (NS_IS_HIGH_SURROGATE(ch) && mPos < mLimit - 1 &&
             NS_IS_LOW_SURROGATE(*(mPos + 1))) {
             ch = SURROGATE_TO_UCS4(ch, *(mPos + 1));
+            chLen = 2;
         }
 
-        if (!IsClusterExtender(ch)) {
+        bool extendCluster = IsClusterExtender(ch) ||
+            (baseIsEmoji && prevWasZwj &&
+                ((GetEmojiPresentation(ch) == EmojiDefault) ||
+                 (GetEmojiPresentation(ch) == TextDefault &&
+                  mPos + chLen < mLimit &&
+                  *(mPos + chLen) == kVS16)));
+        if (!extendCluster) {
             break;
         }
 
-        mPos++;
-        if (!IS_IN_BMP(ch)) {
-            mPos++;
-        }
+        prevWasZwj = (ch == kZWJ);
+        mPos += chLen;
     }
 
     NS_ASSERTION(mText < mPos && mPos <= mLimit,
diff --git a/intl/unicharutil/util/nsUnicodeProperties.h b/intl/unicharutil/util/nsUnicodeProperties.h
index 38fa230625..eaa066b7f6 100644
--- a/intl/unicharutil/util/nsUnicodeProperties.h
+++ b/intl/unicharutil/util/nsUnicodeProperties.h
@@ -180,17 +180,14 @@ IsDefaultIgnorable(uint32_t aCh)
 inline EmojiPresentation
 GetEmojiPresentation(uint32_t aCh)
 {
-  if (u_hasBinaryProperty(aCh, UCHAR_EMOJI_COMPONENT)) {
-    return EmojiComponent;
+  if (!u_hasBinaryProperty(aCh, UCHAR_EMOJI)) {
+    return TextOnly;
   }
-  if (u_hasBinaryProperty(aCh, UCHAR_EMOJI) &&
-     !u_hasBinaryProperty(aCh, UCHAR_EMOJI_PRESENTATION)) {
-    return TextDefault;
-  }
-  if (u_hasBinaryProperty(aCh, UCHAR_EXTENDED_PICTOGRAPHIC)) {
+
+  if (u_hasBinaryProperty(aCh, UCHAR_EMOJI_PRESENTATION)) {
     return EmojiDefault;
   }
-  return TextOnly;
+  return TextDefault;
 }
 
 // returns the simplified Gen Category as defined in nsIUGenCategory