diff --git a/lib/rouge/lexers/common_lisp.rb b/lib/rouge/lexers/common_lisp.rb
index 9357fa2997..4df69bb557 100644
--- a/lib/rouge/lexers/common_lisp.rb
+++ b/lib/rouge/lexers/common_lisp.rb
@@ -320,7 +320,7 @@ class complex concatenated-stream cons echo-stream file-stream
 
         rule /\(/, Punctuation, :root
         rule /\)/, Punctuation do
-          if stack.empty?
+          if stack.size == 1
             token Error
           else
             token Punctuation
diff --git a/spec/lexers/common_lisp_spec.rb b/spec/lexers/common_lisp_spec.rb
index 4c06404363..644b472d64 100644
--- a/spec/lexers/common_lisp_spec.rb
+++ b/spec/lexers/common_lisp_spec.rb
@@ -18,4 +18,12 @@
       assert_guess :mimetype => 'text/x-common-lisp'
     end
   end
+
+  describe 'lexing' do
+    include Support::Lexing
+
+    it 'does not crash on unbalanced parentheses' do
+      subject.lex(")\n").to_a
+    end
+  end
 end
diff --git a/spec/visual/samples/common_lisp b/spec/visual/samples/common_lisp
index a872b4f360..06c88db193 100644
--- a/spec/visual/samples/common_lisp
+++ b/spec/visual/samples/common_lisp
@@ -1,5 +1,8 @@
 #nil (commented (form ftw))
 
+; Unmatched closing parenthesis
+)
+
 ;;;; TYPEP und Verwandtes
 ;;;; Michael Stoll, 21. 10. 1988
 ;;;; Bruno Haible, 10.6.1989