diff --git a/nipype/interfaces/slicer/generate_classes.py b/nipype/interfaces/slicer/generate_classes.py
index fe928cd51f..a36dd6b55a 100644
--- a/nipype/interfaces/slicer/generate_classes.py
+++ b/nipype/interfaces/slicer/generate_classes.py
@@ -45,6 +45,7 @@ def add_class_to_package(class_codes, class_names, module_name, package_dir):
 import os\n\n\n"""
         f_m.write(imports)
         f_m.write("\n\n".join(class_codes))
+    with open(os.path.join(package_dir, "__init__.py"), "a+") as f_i:
         f_i.write("from {} import {}\n".format(module_name, ", ".join(class_names)))