diff --git a/kernel/irq/matrix.c b/kernel/irq/matrix.c
index 7df2480005f8..0ba0dd8863a7 100644
--- a/kernel/irq/matrix.c
+++ b/kernel/irq/matrix.c
@@ -384,7 +384,9 @@ unsigned int irq_matrix_available(struct irq_matrix *m, bool cpudown)
 {
 	struct cpumap *cm = this_cpu_ptr(m->maps);
 
-	return (m->global_available - cpudown) ? cm->available : 0;
+	if (!cpudown)
+		return m->global_available;
+	return m->global_available - cm->available;
 }
 
 /**