diff --git a/compat/mingw.h b/compat/mingw.h
index 47839663be..a2213b3911 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -78,6 +78,12 @@ struct itimerval {
 };
 #define ITIMER_REAL 0
 
+/*
+ * sanitize preprocessor namespace polluted by Windows headers defining
+ * macros which collide with git local versions
+ */
+#undef HELP_COMMAND /* from winuser.h */
+
 /*
  * trivial stubs
  */