diff --git a/Include/cpython/longintrepr.h b/Include/cpython/longintrepr.h
index 9f12298d4fcc37..19a57284e0edb1 100644
--- a/Include/cpython/longintrepr.h
+++ b/Include/cpython/longintrepr.h
@@ -125,9 +125,9 @@ _PyLong_IsCompact(const PyLongObject* op) {
 }
 
 static inline int
-PyLong_CheckCompact(const PyObject *op)
+PyLong_CheckCompact(PyObject *op)
 {
-    return PyLong_CheckExact(op) && _PyLong_IsCompact((PyLongObject *)op);
+    return PyLong_CheckExact(op) && _PyLong_IsCompact((const PyLongObject *)op);
 }
 
 #define PyUnstable_Long_IsCompact _PyLong_IsCompact