diff --git a/src/emu/debug/debugvw.c b/src/emu/debug/debugvw.c
index 49f98c44c9c..90b5bac77f2 100644
--- a/src/emu/debug/debugvw.c
+++ b/src/emu/debug/debugvw.c
@@ -66,7 +66,7 @@ debug_view_source::debug_view_source(const char *name, device_t *device)
 	  m_is_octal(false)
 {
 	device_execute_interface *intf;
-	if (device->interface(intf)) 
+	if (device && device->interface(intf)) 
 		m_is_octal = intf->is_octal();
 
 }