diff --git a/runtime/syntax/sh.yaml b/runtime/syntax/sh.yaml
index 02d176e1..0dbf3952 100644
--- a/runtime/syntax/sh.yaml
+++ b/runtime/syntax/sh.yaml
@@ -36,7 +36,7 @@ rules:
         rules: []
 
     - comment:
-        start: "(^|[[:space:]])#"
+        start: "(^|\\s)#"
         end: "$"
         rules:
             - todo: "(TODO|XXX|FIXME):?"