diff --git a/lib/strings.nix b/lib/strings.nix
index 2e502588bf80..dc287f8dd5cb 100644
--- a/lib/strings.nix
+++ b/lib/strings.nix
@@ -659,7 +659,7 @@ rec {
      Example:
        isStorePath "/nix/store/d945ibfx9x185xf04b890y4f9g3cbb63-python-2.7.11/bin/python"
        => false
-       isStorePath "/nix/store/d945ibfx9x185xf04b890y4f9g3cbb63-python-2.7.11/"
+       isStorePath "/nix/store/d945ibfx9x185xf04b890y4f9g3cbb63-python-2.7.11"
        => true
        isStorePath pkgs.python
        => true