diff --git a/orderbook/orderbook.c b/orderbook/orderbook.c
index fe59f4a..4cb4e56 100644
--- a/orderbook/orderbook.c
+++ b/orderbook/orderbook.c
@@ -540,7 +540,7 @@ static int okx_string_builder(PyObject *pydata, uint8_t *data, int *pos)
     }
 
     // default 'str' formatting is wrong when the value is in scientific notation
-    if (EXPECT(memchr(&data[startpos], (char) 'E', *pos - startpos), 0)) {
+    if (EXPECT((long)memchr(&data[startpos], (char) 'E', *pos - startpos), (long)0)) {
         *pos = startpos;
         if (EXPECT(formatf_string_builder(pydata, data, pos), 0)) {
             return -1;
diff --git a/orderbook/orderbook.h b/orderbook/orderbook.h
index b940d3c..d8f2c08 100644
--- a/orderbook/orderbook.h
+++ b/orderbook/orderbook.h
@@ -121,7 +121,7 @@ static PyModuleDef orderbookmodule = {
     .m_slots = NULL,
     .m_traverse = order_book_traverse,
     .m_clear = order_book_clear,
-    .m_free = order_book_free,
+    .m_free = (void *)order_book_free,
 };