diff --git a/mypy/modulefinder.py b/mypy/modulefinder.py
index baa521afbb12..c5ec268752c6 100644
--- a/mypy/modulefinder.py
+++ b/mypy/modulefinder.py
@@ -711,7 +711,7 @@ def matches_gitignore(subpath: str, fscache: FileSystemCache, verbose: bool) ->
     dir, _ = os.path.split(subpath)
     for gi_path, gi_spec in find_gitignores(dir):
         relative_path = os.path.relpath(subpath, gi_path)
-        if fscache.isdir(relative_path):
+        if fscache.isdir(subpath):
             relative_path = relative_path + "/"
         if gi_spec.match_file(relative_path):
             if verbose: