diff --git a/glib/gbytes.h b/glib/gbytes.h
index a120e211d..de3c8f808 100644
--- a/glib/gbytes.h
+++ b/glib/gbytes.h
@@ -21,6 +21,10 @@
  *         Stef Walter <stefw@collabora.co.uk>
  */
 
+#if !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION)
+#error "Only <glib.h> can be included directly."
+#endif
+
 #ifndef __G_BYTES_H__
 #define __G_BYTES_H__