diff --git a/mypy/fscache.py b/mypy/fscache.py
index 8251f4bd9488..240370159fff 100644
--- a/mypy/fscache.py
+++ b/mypy/fscache.py
@@ -117,7 +117,12 @@ def init_under_package_root(self, path: str) -> bool:
             if not stat.S_ISDIR(st.st_mode):
                 return False
         ok = False
-        drive, path = os.path.splitdrive(path)  # Ignore Windows drive name
+
+        # skip if on a different drive
+        current_drive, _ = os.path.splitdrive(os.getcwd())
+        drive, _ = os.path.splitdrive(path)
+        if drive != current_drive:
+            return False
         if os.path.isabs(path):
             path = os.path.relpath(path)
         path = os.path.normpath(path)