diff --git a/dbus/dbus-macros.h b/dbus/dbus-macros.h
index abcb12a3..4454da3a 100644
--- a/dbus/dbus-macros.h
+++ b/dbus/dbus-macros.h
@@ -24,6 +24,8 @@
 #error "Only <dbus/dbus.h> can be included directly, this file may disappear or change contents."
 #endif
 
+#include <stddef.h>
+
 #ifndef DBUS_MACROS_H
 #define DBUS_MACROS_H