--- a/psutil/arch/all/init.h
+++ b/psutil/arch/all/init.h
@@ -74,6 +74,9 @@ static const int PSUTIL_CONN_NONE = 128;
     #define SIZEOF_PID_T PSUTIL_SIZEOF_PID_T  // set as a macro in setup.py
 #endif
 
+#if __MINGW32__
+    #define _Py_PARSE_PID "i"
+#endif
 // _Py_PARSE_PID was added in Python 3, but since it's private we make
 // sure it's always present.
 #ifndef _Py_PARSE_PID