diff --git a/mypyc/lib-rt/pythonsupport.h b/mypyc/lib-rt/pythonsupport.h
index 85eb6348eb81..69ff120dd40d 100644
--- a/mypyc/lib-rt/pythonsupport.h
+++ b/mypyc/lib-rt/pythonsupport.h
@@ -13,6 +13,18 @@
 #include <assert.h>
 #include "mypyc_util.h"
 
+#if CPY_3_13_FEATURES
+#ifndef Py_BUILD_CORE
+#define Py_BUILD_CORE
+#endif
+#include "internal/pycore_bytesobject.h"  // _PyBytes_Join
+#include "internal/pycore_call.h"  // _PyObject_CallMethodIdNoArgs, _PyObject_CallMethodIdObjArgs, _PyObject_CallMethodIdOneArg
+#include "internal/pycore_genobject.h"  // _PyGen_FetchStopIterationValue
+#include "internal/pycore_object.h"  // _PyType_CalculateMetaclass
+#include "internal/pycore_pyerrors.h"  // _PyErr_FormatFromCause, _PyErr_SetKeyError
+#include "internal/pycore_unicodeobject.h"  // _PyUnicode_EQ, _PyUnicode_FastCopyCharacters
+#endif
+
 #if CPY_3_12_FEATURES
 #include "internal/pycore_frame.h"
 #endif