diff --git a/libs/gtkmm2ext/gtkapplication_quartz.mm b/libs/gtkmm2ext/gtkapplication_quartz.mm
index b628e04140..fc519a6eab 100644
--- a/libs/gtkmm2ext/gtkapplication_quartz.mm
+++ b/libs/gtkmm2ext/gtkapplication_quartz.mm
@@ -41,6 +41,8 @@
 #import <Foundation/NSString.h>
 #import <Foundation/NSNotification.h>
 
+#include "pbd/stacktrace.h"
+
 #include <vector>
 
 #define UNUSED_PARAMETER(a) (void) (a)
@@ -1479,7 +1481,7 @@ namespace Gtk {
 static void
 gdk_quartz_modal_notify (GdkWindow* w, gboolean modal)
 {
-	printf ("modal notify on %p, modal = %d modal_state = %d\n", w, modal, modal_state);
+	printf ("modal notify on %p, modal = %d modal_state = %d\n", w, modal, _modal_state);
 	PBD::stacktrace (std::cerr, 63);
 	/* this global will control sensitivity of our app menu items, via validateMenuItem */
 	if (modal) {