diff --git a/include/linux/irq.h b/include/linux/irq.h
index 1d73d1a..5f4b013 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -179,7 +179,11 @@
 	const char		*name;
 } ____cacheline_internodealigned_in_smp;
 
+#ifdef CONFIG_HAVE_DYN_ARRAY
+extern struct irq_desc *irq_desc;
+#else
 extern struct irq_desc irq_desc[NR_IRQS];
+#endif
 
 /*
  * Migration helpers for obsolete names, they will go away: