diff --git a/src/osd/sdl/sdlmain.c b/src/osd/sdl/sdlmain.c
index 46cfe24b01a..910b493a536 100644
--- a/src/osd/sdl/sdlmain.c
+++ b/src/osd/sdl/sdlmain.c
@@ -24,7 +24,9 @@
 #endif
 
 // standard includes
-
+#ifdef MESS
+#include <unistd.h>
+#endif
 
 #ifdef SDLMAME_OS2
 #define INCL_DOS