diff --git a/dev/core.c b/dev/core.c
index bea49ad..d3abfd0 100644
--- a/dev/core.c
+++ b/dev/core.c
@@ -1,6 +1,7 @@
 #include <socks/status.h>
 #include <socks/object.h>
 #include <socks/device.h>
+#include <socks/printk.h>
 #include <socks/bitmap.h>
 #include <socks/libc/stdio.h>
 
@@ -203,6 +204,13 @@ kern_status_t device_register(struct device *dev, struct driver *owner, struct d
 	device_lock_irqsave(dev, &flags);
 	driver_lock(owner);
 
+	if (owner->drv_major == DEV_MAJOR_INVALID) {
+		driver_unlock(owner);
+		device_unlock_irqrestore(dev, flags);
+		/* TODO better error message for lack of resources? */
+		return KERN_INVALID_ARGUMENT;
+	}
+
 	unsigned int minor = driver_alloc_minor(owner);
 
 	if (minor == DEV_MINOR_INVALID) {
@@ -236,7 +244,6 @@ kern_status_t device_register(struct device *dev, struct driver *owner, struct d
 		break;
 	}
 
-
 	driver_unlock(owner);
 	device_unlock_irqrestore(dev, flags);