diff --git a/devscripts/make_lazy_extractors.py b/devscripts/make_lazy_extractors.py
index 6e3ab754a..4e3514c0d 100644
--- a/devscripts/make_lazy_extractors.py
+++ b/devscripts/make_lazy_extractors.py
@@ -75,7 +75,8 @@ def build_ies(ies, bases, attr_base):
         if ie in ies:
             names.append(ie.__name__)
 
-    yield f'\n_CLASS_LOOKUP = {{ {", ".join(f"'{name}': {name}" for name in names)} }}'
+    class_lookup_contents = ', '.join(f"\'{name}\': {name}" for name in names)
+    yield f'\n_CLASS_LOOKUP = {{ {class_lookup_contents} }}'
 
 
 def sort_ies(ies, ignored_bases):