diff --git a/grammar.js b/grammar.js
index f18337d..b6e4702 100644
--- a/grammar.js
+++ b/grammar.js
@@ -39,7 +39,9 @@ module.exports = grammar({
     $._attr_value_ruby_p, // ()
     $._attr_value_ruby_s, // []
     $._attr_value_ruby_b, // {}
-    $.ruby
+    $.ruby,
+
+    $._error_sentinel
   ],
 
   rules: {
diff --git a/src/grammar.json b/src/grammar.json
index f5913ba..6689bb6 100644
--- a/src/grammar.json
+++ b/src/grammar.json
@@ -1579,6 +1579,10 @@
     {
       "type": "SYMBOL",
       "name": "ruby"
+    },
+    {
+      "type": "SYMBOL",
+      "name": "_error_sentinel"
     }
   ],
   "inline": [],
diff --git a/src/scanner.cc b/src/scanner.cc
index 1d33cd1..b555f4b 100644
--- a/src/scanner.cc
+++ b/src/scanner.cc
@@ -18,7 +18,9 @@ enum TokenType {
   ATTR_VALUE_RUBY_P,
   ATTR_VALUE_RUBY_S,
   ATTR_VALUE_RUBY_B,
-  RUBY
+  RUBY,
+
+  ERROR_SENTINEL
 };
 
 class Scanner {
@@ -186,7 +188,7 @@ class Scanner {
       }
     }
 
-    if (valid_symbols[RUBY]) {
+    if (valid_symbols[RUBY] && !valid_symbols[ERROR_SENTINEL]) {
       return scan_ruby(lexer);
     }