diff --git a/bson/_cbsonmodule.c b/bson/_cbsonmodule.c
index a5bc66f0c..2632e2f33 100644
--- a/bson/_cbsonmodule.c
+++ b/bson/_cbsonmodule.c
@@ -599,8 +599,7 @@ fail:
  * Return 1 on success. options->document_class is a new reference.
  * Return 0 on failure.
  */
-int convert_codec_options(PyObject* self, PyObject* options_obj, void* p) {
-    codec_options_t* options = (codec_options_t*)p;
+int convert_codec_options(PyObject* self, PyObject* options_obj, codec_options_t* options) {
     PyObject* type_registry_obj = NULL;
     long type_marker;
 
@@ -613,8 +612,9 @@ int convert_codec_options(PyObject* self, PyObject* options_obj, void* p) {
                           &options->unicode_decode_error_handler,
                           &options->tzinfo,
                           &type_registry_obj,
-                          &options->datetime_conversion))
+                          &options->datetime_conversion)) {
         return 0;
+    }
 
     type_marker = _type_marker(options->document_class,
                                GETSTATE(self)->_type_marker_str);
diff --git a/bson/_cbsonmodule.h b/bson/_cbsonmodule.h
index b7b92538e..3be2b7442 100644
--- a/bson/_cbsonmodule.h
+++ b/bson/_cbsonmodule.h
@@ -93,7 +93,7 @@ typedef struct codec_options_t {
 
 #define _cbson_convert_codec_options_INDEX 4
 #define _cbson_convert_codec_options_RETURN int
-#define _cbson_convert_codec_options_PROTO (PyObject* self, PyObject* options_obj, void* p)
+#define _cbson_convert_codec_options_PROTO (PyObject* self, PyObject* options_obj, codec_options_t* options)
 
 #define _cbson_destroy_codec_options_INDEX 5
 #define _cbson_destroy_codec_options_RETURN void