diff --git a/sys/compat/linuxkpi/common/include/linux/radix-tree.h b/sys/compat/linuxkpi/common/include/linux/radix-tree.h
index a1204cb20a7..48fbb9e26c4 100644
--- a/sys/compat/linuxkpi/common/include/linux/radix-tree.h
+++ b/sys/compat/linuxkpi/common/include/linux/radix-tree.h
@@ -73,11 +73,11 @@ radix_tree_exception(void *arg)
 	return ((uintptr_t)arg & RADIX_TREE_ENTRY_MASK);
 }
 
-void	*radix_tree_lookup(struct radix_tree_root *, unsigned long);
+void	*radix_tree_lookup(const struct radix_tree_root *, unsigned long);
 void	*radix_tree_delete(struct radix_tree_root *, unsigned long);
 int	radix_tree_insert(struct radix_tree_root *, unsigned long, void *);
 int	radix_tree_store(struct radix_tree_root *, unsigned long, void **);
-bool	radix_tree_iter_find(struct radix_tree_root *, struct radix_tree_iter *, void ***);
+bool	radix_tree_iter_find(const struct radix_tree_root *, struct radix_tree_iter *, void ***);
 void	radix_tree_iter_delete(struct radix_tree_root *, struct radix_tree_iter *, void **);
 
 #endif	/* _LINUXKPI_LINUX_RADIX_TREE_H_ */
diff --git a/sys/compat/linuxkpi/common/src/linux_radix.c b/sys/compat/linuxkpi/common/src/linux_radix.c
index f0f7cce128e..01f493877a5 100644
--- a/sys/compat/linuxkpi/common/src/linux_radix.c
+++ b/sys/compat/linuxkpi/common/src/linux_radix.c
@@ -42,7 +42,7 @@
 static MALLOC_DEFINE(M_RADIX, "radix", "Linux radix compat");
 
 static inline unsigned long
-radix_max(struct radix_tree_root *root)
+radix_max(const struct radix_tree_root *root)
 {
 	return ((1UL << (root->height * RADIX_TREE_MAP_SHIFT)) - 1UL);
 }
@@ -65,7 +65,7 @@ radix_tree_clean_root_node(struct radix_tree_root *root)
 }
 
 void *
-radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
+radix_tree_lookup(const struct radix_tree_root *root, unsigned long index)
 {
 	struct radix_tree_node *node;
 	void *item;
@@ -86,8 +86,8 @@ out:
 }
 
 bool
-radix_tree_iter_find(struct radix_tree_root *root, struct radix_tree_iter *iter,
-    void ***pppslot)
+radix_tree_iter_find(const struct radix_tree_root *root,
+    struct radix_tree_iter *iter, void ***pppslot)
 {
 	struct radix_tree_node *node;
 	unsigned long index = iter->index;