diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index be86b32bc874..8d3fb0bd1288 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -81,7 +81,7 @@ struct radix_tree_preload {
 	int nr;
 	struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
 };
-DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
+static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
 
 static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
 {