diff --git a/url/url_canon_fileurl.cc b/url/url_canon_fileurl.cc
index 6277289..067ed58 100644
--- a/url/url_canon_fileurl.cc
+++ b/url/url_canon_fileurl.cc
@@ -76,8 +76,8 @@
     Component sub_path = MakeRange(after_drive, path.end());
     Component fake_output_path;
     success = CanonicalizePath(spec, sub_path, output, &fake_output_path);
-  } else {
-    // No input path, canonicalize to a slash.
+  } else if (after_drive == path.begin) {
+    // No input path and no drive spec, canonicalize to a slash.
     output->push_back('/');
   }