Index: sys/x86/xen/xen_intr.c
===================================================================
--- sys/x86/xen/xen_intr.c
+++ sys/x86/xen/xen_intr.c
@@ -331,7 +331,10 @@
 	isrc->xi_intsrc.is_pic = &xen_intr_pic;
 	isrc->xi_vector = vector;
 	isrc->xi_type = type;
-	intr_register_source(&isrc->xi_intsrc);
+	if (intr_register_source(&isrc->xi_intsrc) != 0) {
+		free(isrc, M_XENINTR);
+		isrc = NULL;
+	}
 	mtx_lock(&xen_intr_isrc_lock);
 
 	return (isrc);