diff --git a/capnp/lib/capnp.pyx b/capnp/lib/capnp.pyx
index 414f19a..a3ec1dd 100644
--- a/capnp/lib/capnp.pyx
+++ b/capnp/lib/capnp.pyx
@@ -4026,7 +4026,7 @@ class _Importer:
             has_underscores = True
 
         if package_path:
-            paths = package_path
+            paths = list(package_path)
         else:
             paths = _sys.path
         join_path = _os.path.join