diff --git a/gtk2_ardour/cairo_widget.cc b/gtk2_ardour/cairo_widget.cc
index 28d7068bc0..209770ab03 100644
--- a/gtk2_ardour/cairo_widget.cc
+++ b/gtk2_ardour/cairo_widget.cc
@@ -32,7 +32,7 @@ CairoWidget::CairoWidget ()
 CairoWidget::~CairoWidget ()
 {
 	if (_pixmap) {
-		gdk_pixmap_unref (_pixmap);
+		g_object_unref (_pixmap);
 	}
 }
 
@@ -55,7 +55,7 @@ CairoWidget::on_expose_event (GdkEventExpose *event)
 		if (_dirty) {
 
 			if (_pixmap) {
-				gdk_pixmap_unref (_pixmap);
+				g_object_unref (_pixmap);
 			}
 
 			_pixmap = gdk_pixmap_new (drawable, _width, _height, -1);
diff --git a/gtk2_ardour/port_matrix_column_labels.cc b/gtk2_ardour/port_matrix_column_labels.cc
index c3b10e289b..339767f27d 100644
--- a/gtk2_ardour/port_matrix_column_labels.cc
+++ b/gtk2_ardour/port_matrix_column_labels.cc
@@ -91,7 +91,7 @@ PortMatrixColumnLabels::compute_dimensions ()
 	}
 
 	cairo_destroy (cr);
-	gdk_pixmap_unref (pm);
+	g_object_unref (pm);
 
 	/* height of the whole thing */
 
diff --git a/gtk2_ardour/port_matrix_component.cc b/gtk2_ardour/port_matrix_component.cc
index 9652a38f21..440376d1fa 100644
--- a/gtk2_ardour/port_matrix_component.cc
+++ b/gtk2_ardour/port_matrix_component.cc
@@ -41,7 +41,7 @@ PortMatrixComponent::PortMatrixComponent (PortMatrix* m, PortMatrixBody* b)
 PortMatrixComponent::~PortMatrixComponent ()
 {
 	if (_pixmap) {
-		gdk_pixmap_unref (_pixmap);
+		g_object_unref (_pixmap);
 	}
 }
 
@@ -74,7 +74,7 @@ PortMatrixComponent::get_pixmap (GdkDrawable *drawable)
 
 		/* make a pixmap of the right size */
 		if (_pixmap) {
-			gdk_pixmap_unref (_pixmap);
+			g_object_unref (_pixmap);
 		}
 		_pixmap = gdk_pixmap_new (drawable, _width, _height, -1);
 
diff --git a/gtk2_ardour/port_matrix_row_labels.cc b/gtk2_ardour/port_matrix_row_labels.cc
index 2bf2b70a27..57e972acd4 100644
--- a/gtk2_ardour/port_matrix_row_labels.cc
+++ b/gtk2_ardour/port_matrix_row_labels.cc
@@ -78,7 +78,7 @@ PortMatrixRowLabels::compute_dimensions ()
 	}
 
 	cairo_destroy (cr);
-	gdk_pixmap_unref (pm);
+	g_object_unref (pm);
 
 	_width = _longest_bundle_name +
 		name_pad() * 2;