diff --git a/doc_src/cmds/string-length.rst b/doc_src/cmds/string-length.rst
index d5a9ca359..1cb84058e 100644
--- a/doc_src/cmds/string-length.rst
+++ b/doc_src/cmds/string-length.rst
@@ -34,6 +34,6 @@ Examples
     >_ set str foo
     >_ string length -q $str; echo $status
     0
-    # Equivalent to test -n $str
+    # Equivalent to test -n "$str"
 
 .. END EXAMPLES