diff --git a/platformio/managers/package.py b/platformio/managers/package.py
index 905b756a..29761195 100644
--- a/platformio/managers/package.py
+++ b/platformio/managers/package.py
@@ -478,7 +478,7 @@ class PkgInstallerMixin(object):
                     target_dirname = "%s@src-%s" % (
                         pkg_dirname,
                         hashlib.md5(cur_manifest['__src_url']).hexdigest())
-                os.rename(pkg_dir, join(self.package_dir, target_dirname))
+                os.rename(pkg_dir, join(self.package_dir, str(target_dirname)))
             # fix to a version
             elif action == 2:
                 target_dirname = "%s@%s" % (pkg_dirname,