diff --git a/grammars/sass.cson b/grammars/sass.cson
index 8481d56..9206c49 100644
--- a/grammars/sass.cson
+++ b/grammars/sass.cson
@@ -654,8 +654,8 @@
         'include': '#variable-usage'
       }
       {
-        'match': '\\b(true|false)\\b'
-        'name': 'support.constant.property-value.css.sass'
+        'match': '\\b(true|false|null)\\b'
+        'name': 'support.constant.property-value.sass'
       }
       {
         'include': 'source.css#property-keywords'