diff --git a/lib/idr.c b/lib/idr.c
index 3476f82..e728c7f 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -607,7 +607,7 @@
 }
 EXPORT_SYMBOL(idr_replace);
 
-static void idr_cache_ctor(struct kmem_cache *idr_layer_cache, void *idr_layer)
+static void idr_cache_ctor(void *idr_layer)
 {
 	memset(idr_layer, 0, sizeof(struct idr_layer));
 }