diff --git a/mode/yaml/yaml.js b/mode/yaml/yaml.js
index 298db55f6f..895d1330a2 100644
--- a/mode/yaml/yaml.js
+++ b/mode/yaml/yaml.js
@@ -85,7 +85,7 @@ CodeMirror.defineMode("yaml", function() {
       }
 
       /* pairs (associative arrays) -> key */
-      if (!state.pair && stream.match(/^\s*(?:[,\[\]{}&*!|>'"%@`][^\s'":]|[^,\[\]{}#&*!|>'"%@`])[^#]*?(?=\s*:($|\s))/)) {
+      if (!state.pair && stream.match(/^\s*(?:[,\[\]{}&*!|>'"%@`][^\s'":]|[^\s,\[\]{}#&*!|>'"%@`])[^#:]*(?=:($|\s))/)) {
         state.pair = true;
         state.keyCol = stream.indentation();
         return "atom";