diff --git a/codegen.py b/codegen.py
index 24d36a0..7f92521 100644
--- a/codegen.py
+++ b/codegen.py
@@ -33,7 +33,7 @@ def main():
     startup.
     """
 
-    with open("tracking_numbers/_generated.py", "w") as wf:
+    with open("tracking_numbers/_generated.py", "w", encoding="utf-8") as wf:
         wf.write("# DO NOT EDIT - Generated by codegen.py\n")
         wf.write("\n")
         for import_stmt in import_statements:
diff --git a/tracking_numbers/helpers/spec.py b/tracking_numbers/helpers/spec.py
index cc770b7..630cf46 100644
--- a/tracking_numbers/helpers/spec.py
+++ b/tracking_numbers/helpers/spec.py
@@ -16,7 +16,7 @@
 def iter_courier_specs(base_dir: str = DEFAULT_BASE_DIR):
     for filename in listdir(base_dir):
         path = os.path.join(base_dir, filename)
-        with open(path) as f:
+        with open(path, encoding="utf-8") as f:
             yield json.load(f)