Index: uspace/drv/fb/kfb/port.c
===================================================================
--- uspace/drv/fb/kfb/port.c	(revision b669092e438e076884593e6fbe1d1d1da54b83a3)
+++ uspace/drv/fb/kfb/port.c	(revision f4665bdceacaf4ffbcf2ed2610a92456199e2352)
@@ -95,9 +95,16 @@
 static int kfb_yield(visualizer_t *vs)
 {
+	int rc;
+
 	if (vs->mode_set) {
 		vs->ops.handle_damage = NULL;
 	}
 
-	return physmem_unmap(kfb.addr);
+	rc = physmem_unmap(kfb.addr);
+	if (rc != EOK)
+		return rc;
+
+	kfb.addr = NULL;
+	return EOK;
 }
 
@@ -158,7 +165,14 @@
 {
 	visualizer_t *vsl;
+	int rc;
 
 	vsl = (visualizer_t *) ddf_fun_data_get((ddf_fun_t *)arg);
 	graph_visualizer_connection(vsl, iid, icall, NULL);
+
+	if (kfb.addr != NULL) {
+		rc = physmem_unmap(kfb.addr);
+		if (rc == EOK)
+			kfb.addr = NULL;
+	}
 }