diff --git a/src/doomtype.h b/src/doomtype.h
index e6da5e50c7499c13de51a4597689e721dab8151f..c59e1738135ac577024355b415a43bfca981431f 100644
--- a/src/doomtype.h
+++ b/src/doomtype.h
@@ -139,7 +139,7 @@ size_t strlcpy(char *dst, const char *src, size_t siz);
 #ifndef _WIN32
 typedef int32_t boolean;
 #else
-#define BOOL boolean
+#define boolean BOOL
 #endif
 
 #ifndef __cplusplus