diff --git a/schema_salad/metaschema.py b/schema_salad/metaschema.py
index 71b0d56f..0368e876 100644
--- a/schema_salad/metaschema.py
+++ b/schema_salad/metaschema.py
@@ -140,10 +140,10 @@ def __init__(
         self.vocab = _vocab
         self.rvocab = _rvocab
 
-        if namespaces is not None:
+        if self.namespaces is not None:
             self.vocab = self.vocab.copy()
             self.rvocab = self.rvocab.copy()
-            for k, v in namespaces.items():
+            for k, v in self.namespaces.items():
                 self.vocab[k] = v
                 self.rvocab[v] = k
 
diff --git a/schema_salad/python_codegen_support.py b/schema_salad/python_codegen_support.py
index c89b42db..ec0d64b0 100644
--- a/schema_salad/python_codegen_support.py
+++ b/schema_salad/python_codegen_support.py
@@ -137,10 +137,10 @@ def __init__(
         self.vocab = _vocab
         self.rvocab = _rvocab
 
-        if namespaces is not None:
+        if self.namespaces is not None:
             self.vocab = self.vocab.copy()
             self.rvocab = self.rvocab.copy()
-            for k, v in namespaces.items():
+            for k, v in self.namespaces.items():
                 self.vocab[k] = v
                 self.rvocab[v] = k