diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,10 @@
 # Revision history for skylighting and skylighting-core
 
+## 0.10.0.2
+
+  * Improve DetectIdentifier to ensure that identifiers can't
+    include non-ASCII characters.
+
 ## 0.10.0.1
 
   * Fix identifier detection in non-ASCII context (#110).
diff --git a/skylighting-core.cabal b/skylighting-core.cabal
--- a/skylighting-core.cabal
+++ b/skylighting-core.cabal
@@ -1,5 +1,5 @@
 name:                skylighting-core
-version:             0.10.0.1
+version:             0.10.0.2
 synopsis:            syntax highlighting library
 description:         Skylighting is a syntax highlighting library.
                      It derives its tokenizers from XML syntax
diff --git a/src/Skylighting/Tokenizer.hs b/src/Skylighting/Tokenizer.hs
--- a/src/Skylighting/Tokenizer.hs
+++ b/src/Skylighting/Tokenizer.hs
@@ -497,7 +497,7 @@
   case BS.uncons inp of
     Just (c, t) | (isAscii c && isLetter c) || c == '_' ->
       takeChars $ 1 + maybe (BS.length t) id
-                (BS.findIndex (\d -> isAscii d &&
+                (BS.findIndex (\d -> not (isAscii d) ||
                                      not (isAlphaNum d || d == '_')) t)
     _ -> mzero