diff --git a/drivers/isdn/gigaset/common.c b/drivers/isdn/gigaset/common.c
index 4f75cce..9d4ae04 100644
--- a/drivers/isdn/gigaset/common.c
+++ b/drivers/isdn/gigaset/common.c
@@ -640,7 +640,6 @@
 		return NULL;
 	}
 	mutex_init(&cs->mutex);
-	mutex_lock(&cs->mutex);
 
 	gig_dbg(DEBUG_INIT, "allocating bcs[0..%d]", channels - 1);
 	cs->bcs = kmalloc(channels * sizeof(struct bc_state), GFP_KERNEL);
@@ -738,6 +737,7 @@
 
 	++cs->cs_init;
 
+	/* set up character device */
 	gigaset_if_init(cs);
 
 	/* set up device sysfs */
@@ -753,11 +753,9 @@
 	add_timer(&cs->timer);
 
 	gig_dbg(DEBUG_INIT, "cs initialized");
-	mutex_unlock(&cs->mutex);
 	return cs;
 
 error:
-	mutex_unlock(&cs->mutex);
 	gig_dbg(DEBUG_INIT, "failed");
 	gigaset_freecs(cs);
 	return NULL;
diff --git a/drivers/isdn/gigaset/interface.c b/drivers/isdn/gigaset/interface.c
index f13de20..eb50f3d 100644
--- a/drivers/isdn/gigaset/interface.c
+++ b/drivers/isdn/gigaset/interface.c
@@ -615,6 +615,8 @@
 		return;
 
 	tasklet_init(&cs->if_wake_tasklet, &if_wake, (unsigned long) cs);
+
+	mutex_lock(&cs->mutex);
 	cs->tty_dev = tty_register_device(drv->tty, cs->minor_index, NULL);
 
 	if (!IS_ERR(cs->tty_dev))
@@ -623,6 +625,7 @@
 		warn("could not register device to the tty subsystem");
 		cs->tty_dev = NULL;
 	}
+	mutex_unlock(&cs->mutex);
 }
 
 void gigaset_if_free(struct cardstate *cs)