diff --git a/Modules/_ctypes/malloc_closure.c b/Modules/_ctypes/malloc_closure.c
index 788bae6a9..3938f79db 100644
--- a/Modules/_ctypes/malloc_closure.c
+++ b/Modules/_ctypes/malloc_closure.c
@@ -11,6 +11,9 @@
 #endif
 #include "ctypes.h"
 
+#undef Py_ffi_closure_alloc
+#undef Py_ffi_closure_free
+
 /* BLOCKSIZE can be adjusted.  Larger blocksize will take a larger memory
    overhead, but allocate less blocks from the system.  It may be that some
    systems have a limit of how many mmap'd blocks can be open.