diff --git a/src/emu/machine/netlist.h b/src/emu/machine/netlist.h
index a94a89b90be..561179fafc9 100644
--- a/src/emu/machine/netlist.h
+++ b/src/emu/machine/netlist.h
@@ -262,7 +262,7 @@ private:
 // net_output_t
 // ----------------------------------------------------------------------------------------
 
-struct net_output_t
+class net_output_t
 {
 public:
 	net_output_t();