diff --git a/docs/revsets.md b/docs/revsets.md
index b32e97651..cbba30ed3 100644
--- a/docs/revsets.md
+++ b/docs/revsets.md
@@ -141,8 +141,8 @@ revsets (expressions) as arguments.
 
 Functions that perform string matching support the following pattern syntax.
 
-* `"substring"`: Matches strings that contain `substring`.
-* `literal:"string"`:  Matches strings exactly equal to `string`.
+* `"string"`, `substring:"string"`: Matches strings that contain `string`.
+* `literal:"string"`: Matches strings exactly equal to `string`.
 
 ## Aliases
 
diff --git a/lib/src/revset.rs b/lib/src/revset.rs
index 5097578f4..efc3e95a3 100644
--- a/lib/src/revset.rs
+++ b/lib/src/revset.rs
@@ -1324,7 +1324,7 @@ fn parse_function_argument_to_string_pattern(
             };
             match kind.as_ref() {
                 "literal" => StringPattern::Literal(needle.clone()),
-                // TODO: maybe add explicit kind for substring match?
+                "substring" => StringPattern::Substring(needle.clone()),
                 _ => {
                     // TODO: error span can be narrowed to the lhs node
                     return Err(make_error(format!(
@@ -2699,6 +2699,12 @@ mod tests {
                 "foo".to_owned()
             )))
         );
+        assert_eq!(
+            parse(r#"branches(substring:"foo")"#),
+            Ok(RevsetExpression::branches(StringPattern::Substring(
+                "foo".to_owned()
+            )))
+        );
         assert_eq!(
             parse(r#"branches("literal:foo")"#),
             Ok(RevsetExpression::branches(StringPattern::Substring(