diff --git a/syntax/gas.vim b/syntax/gas.vim
index 93b4ae7..70b849b 100644
--- a/syntax/gas.vim
+++ b/syntax/gas.vim
@@ -70,7 +70,7 @@ syn match   gasSpecial		/\<[$.]\>/
 
 " constants
 syn region  gasString		start=/"/  end=/"/ skip=/\\./
-syn match   gasCharacter	/'\(?\|\\?\)/
+syn match   gasCharacter	/'\([^']\|\\.\)'/
 syn match   gasDecimalNumber	/\$\?-\?\d\+/
 syn match   gasBinaryNumber	/\$\?-\?0b[01]\+/
 syn match   gasOctalNumber	/\$\?-\?0\d\+/