diff --git a/crates/acp_thread/src/mention.rs b/crates/acp_thread/src/mention.rs
index 0b6c0b482b8b048dbb0f6c4c3991a6255a1ef548..bbcf31a4fa2f0307987999af0543624bec05972c 100644
--- a/crates/acp_thread/src/mention.rs
+++ b/crates/acp_thread/src/mention.rs
@@ -506,6 +506,15 @@ mod tests {
         assert_eq!(parsed.to_uri().to_string(), file_uri);
     }
 
+    #[test]
+    fn test_directory_uri_inserts_trailing_slash() {
+        let uri = MentionUri::Directory {
+            abs_path: PathBuf::from(path!("/path/to/dir")),
+        };
+        let expected = uri!("file:///path/to/dir/");
+        assert_eq!(uri.to_uri().to_string(), expected);
+    }
+
     #[test]
     fn test_to_directory_uri_without_slash() {
         let uri = MentionUri::Directory {