diff --git a/src/os_beos.h b/src/os_beos.h
index 260834e..e55c389 100644
--- a/src/os_beos.h
+++ b/src/os_beos.h
@@ -22,4 +22,6 @@
 
 /* select emulation */
 
-#include <net/socket.h>		/* for typedefs and #defines only */
+#ifndef PROTO
+# include <net/socket.h>		/* for typedefs and #defines only */
+#endif