diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,12 @@
 # Changelog for commonmark-extensions
 
+## 0.2.5.5
+
+  * Fix auto_identifiers extension: it now replaces emojis with
+    their aliases, as documented.
+  * Fix auto_identifiers_ascii extension: it now ignores
+    non-ASCII characters with no ASCII equivalent.
+
 ## 0.2.5.4
 
   * Fix autolink parsing regression (#151). This affects autolinks with
diff --git a/commonmark-extensions.cabal b/commonmark-extensions.cabal
--- a/commonmark-extensions.cabal
+++ b/commonmark-extensions.cabal
@@ -1,5 +1,5 @@
 name:           commonmark-extensions
-version:        0.2.5.4
+version:        0.2.5.5
 synopsis:       Pure Haskell commonmark parser.
 description:
    This library provides some useful extensions to core commonmark
@@ -62,7 +62,7 @@
     , network-uri
     , commonmark >= 0.2.4.1 && < 0.3
     -- for extensions:
-    , emojis >= 0.1 && < 0.2
+    , emojis >= 0.1.4.1 && < 0.2
   exposed-modules:
       Commonmark.Extensions
       Commonmark.Extensions.Smart
diff --git a/src/Commonmark/Extensions/AutoIdentifiers.hs b/src/Commonmark/Extensions/AutoIdentifiers.hs
--- a/src/Commonmark/Extensions/AutoIdentifiers.hs
+++ b/src/Commonmark/Extensions/AutoIdentifiers.hs
@@ -16,6 +16,7 @@
 import Data.Dynamic
 import qualified Data.Map as M
 import qualified Data.Text as T
+import qualified Text.Emoji as Emoji
 import Text.Parsec
 
 autoIdentifiersSpec :: (Monad m, IsBlock il bl, IsInline il, ToPlainText il)
@@ -49,7 +50,8 @@
       Nothing  -> do
         contents <- runInlineParser
                     (removeIndent . mconcat . reverse . blockLines $ bd)
-        let ident = makeIdentifier ascii (toPlainText contents)
+        let ident = makeIdentifier ascii
+                     (Emoji.replaceEmojis emojiToAlias $ toPlainText contents)
         counterMap <- counters <$> getState
         let key = "identifier:" <> ident
         cnt <- case M.lookup key counterMap of
@@ -64,6 +66,10 @@
       Just _ -> return $! bd
   | otherwise = return $! bd
 
+emojiToAlias :: T.Text -> [T.Text] -> T.Text
+emojiToAlias t [] = t
+emojiToAlias _ (a:_) = a
+
 makeIdentifier :: Bool -> T.Text -> T.Text
 makeIdentifier ascii = toIdent . T.toLower
   where
@@ -76,9 +82,13 @@
                     = fromchar c
         | otherwise = mempty
     fromchar c
-      | ascii
-      , not (isAscii c) = maybe mempty T.singleton $ M.lookup c asciiMap
-      | otherwise       = T.singleton c
+      | ascii =
+        if isAscii c
+           then T.singleton c
+           else case M.lookup c asciiMap of
+                       Nothing -> mempty
+                       Just d -> T.singleton d
+      | otherwise = T.singleton c
 
 asciiMap :: M.Map Char Char
 asciiMap = M.fromList
diff --git a/test/auto_identifiers.md b/test/auto_identifiers.md
--- a/test/auto_identifiers.md
+++ b/test/auto_identifiers.md
@@ -82,3 +82,11 @@
 <h1 id="hi-2">Hi</h1>
 <h1 id="hi-3">Hi</h1>
 ````````````````````````````````
+
+Emojis should be replaced with aliases:
+
+```
+# Introduction ❤️💯
+.
+<h1 id="introduction-heart-100">Introduction ❤️💯</h1>
+```
diff --git a/test/auto_identifiers_ascii.md b/test/auto_identifiers_ascii.md
--- a/test/auto_identifiers_ascii.md
+++ b/test/auto_identifiers_ascii.md
@@ -3,10 +3,17 @@
 The `auto_identifiers_ascii` extension is like
 `auto_identifiers` but limits identifiers to ASCII.
 Accented Latin characters are converted into the
-closest ASCII equivalent.
+closest ASCII equivalent. Other non-ASCII characters
+are simply omitted.
 
 ```````````````````````````````` example
-# Heading with &auml;
+# Heading with &auml; and &alpha;
 .
-<h1 id="heading-with-a">Heading with &auml;</h1>
+<h1 id="heading-with-a-and-">Heading with ä and α</h1>
+````````````````````````````````
+
+```````````````````````````````` example
+# Heading with ❤️
+.
+<h1 id="heading-with-heart">Heading with ❤️</h1>
 ````````````````````````````````
diff --git a/test/test-commonmark-extensions.hs b/test/test-commonmark-extensions.hs
--- a/test/test-commonmark-extensions.hs
+++ b/test/test-commonmark-extensions.hs
@@ -45,6 +45,7 @@
              , ("test/bracketed_spans.md", bracketedSpanSpec)
              , ("test/fenced_divs.md", fencedDivSpec)
              , ("test/auto_identifiers.md", autoIdentifiersSpec <> attributesSpec)
+             , ("test/auto_identifiers_ascii.md", autoIdentifiersAsciiSpec <> attributesSpec)
              , ("test/implicit_heading_references.md",
                  autoIdentifiersSpec <> attributesSpec <> implicitHeadingReferencesSpec)
              , ("test/wikilinks_title_before_pipe.md", wikilinksSpec TitleBeforePipe)