diff --git a/sys/kern/subr_intr.c b/sys/kern/subr_intr.c
--- a/sys/kern/subr_intr.c
+++ b/sys/kern/subr_intr.c
@@ -469,7 +469,7 @@
 	mtx_assert(&isrc_table_lock, MA_OWNED);
 
 	if (isrc->isrc_irq >= intr_nirq)
-		return (EINVAL);
+		return (0);
 	if (irq_sources[isrc->isrc_irq] != isrc)
 		return (EINVAL);
 
@@ -537,7 +537,11 @@
 		isrc_release_counters(isrc);
 	error = isrc_free_irq(isrc);
 	mtx_unlock(&isrc_table_lock);
-	return (error);
+
+	if (error != 0)
+		return (error);
+
+	return (intr_event_destroy(isrc->isrc_event));
 }
 
 #ifdef SMP