diff --git a/lsp_bridge.py b/lsp_bridge.py
index ed53fb9e9d..4eb1da5c0c 100755
--- a/lsp_bridge.py
+++ b/lsp_bridge.py
@@ -754,9 +754,13 @@ def load_single_lang_server(self, project_path, filepath):
 
         lang_server_info = load_single_server_info(single_lang_server)
 
+        # If project_path is file path, not dir.
         if ((not os.path.isdir(project_path)) and
-            "support-single-file" in lang_server_info and
-            lang_server_info["support-single-file"] is False):
+            # Try to find "project-files" option to detect project root.
+            # support-single-file is False or support-single-file option is not exist.
+            (("support-single-file" in lang_server_info and
+                 lang_server_info["support-single-file"] is False) or
+             ("support-single-file" not in lang_server_info))):
 
             if "project-files" in lang_server_info:
                 # If support-support-single-file is False,