diff --git a/src/osd/sdl/sdlmisc_macosx.c b/src/osd/sdl/sdlmisc_macosx.c
index b80e74745c5..7cbd3b86cfd 100644
--- a/src/osd/sdl/sdlmisc_macosx.c
+++ b/src/osd/sdl/sdlmisc_macosx.c
@@ -14,6 +14,9 @@
 #include <sys/types.h>
 #include <sys/mman.h>
 #include <signal.h>
+#ifdef MAME_DEBUG
+#include <unistd.h>
+#endif
 
 
 // MAME headers
diff --git a/src/osd/sdl/sdlmisc_unix.c b/src/osd/sdl/sdlmisc_unix.c
index efd2d27d4a1..f133f8c6ec7 100644
--- a/src/osd/sdl/sdlmisc_unix.c
+++ b/src/osd/sdl/sdlmisc_unix.c
@@ -11,6 +11,9 @@
 
 #include <sys/mman.h>
 #include <signal.h>
+#ifdef MAME_DEBUG
+#include <unistd.h>
+#endif
 
 // MAME headers
 #include "osdcore.h"