diff --git a/dep/g3dlite/include/G3D/GMutex.h b/dep/g3dlite/include/G3D/GMutex.h
index 3469b81..9fe098d 100644
--- a/dep/g3dlite/include/G3D/GMutex.h
+++ b/dep/g3dlite/include/G3D/GMutex.h
@@ -16,6 +16,7 @@
 #ifndef G3D_WIN32
 #   include <pthread.h>
 #   include <signal.h>
+#   include <unistd.h>
 #endif