diff --git a/src/main/main.cpp b/src/main/main.cpp
index c25c182..68b879a 100644
--- a/src/main/main.cpp
+++ b/src/main/main.cpp
@@ -18,6 +18,13 @@
 #else
 #include "SDL2/SDL.h"
 #include "SDL2/SDL_syswm.h"
+// Undefine x11 macros that get included by SDL_syswm.h.
+#undef None
+#undef Status
+#undef LockMask
+#undef ControlMask
+#undef Success
+#undef Always
 #endif
 
 #include "recomp_ui.h"