diff --git a/Modules/_multiprocessing/multiprocessing.h b/Modules/_multiprocessing/multiprocessing.h
index 2bfad875017..4f4f9d735e7 100644
--- a/Modules/_multiprocessing/multiprocessing.h
+++ b/Modules/_multiprocessing/multiprocessing.h
@@ -16,6 +16,9 @@
 #  include <windows.h>
 #  include <winsock2.h>
 #  include <process.h>		     /* getpid() */
+#  ifdef Py_DEBUG
+#    include <crtdbg.h>
+#  endif
 #  define SEM_HANDLE HANDLE
 #  define SEM_VALUE_MAX LONG_MAX
 #else