diff --git a/docs/config.md b/docs/config.md
index 54b89c0b2..bdfc03ead 100644
--- a/docs/config.md
+++ b/docs/config.md
@@ -189,7 +189,7 @@ users:
 revset-aliases."immutable_heads()" = "main@origin | (main@origin.. & ~mine())"
 ```
 
-Ancestors of the configured set are also immutable. The root commit always
+Ancestors of the configured set are also immutable. The root commit is always
 immutable even if the set is empty.
 
 ### Default revisions to log