diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 1b7bf73..368f641 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -91,9 +91,15 @@ static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node)
 }
 #endif
 
+/*
+ * The slot pointer must be a real pointer as GCC will optimise
+ * through inlined functions and may deduce that
+ * parent->slots + get_slot_offset(parent, slot) == slot
+ */
 static inline unsigned long get_slot_offset(struct radix_tree_node *parent,
 						 void **slot)
 {
+	BUG_ON(radix_tree_exception(slot));
 	return slot - parent->slots;
 }
 
@@ -101,11 +107,12 @@ static unsigned int radix_tree_descend(struct radix_tree_node *parent,
 			struct radix_tree_node **nodep, unsigned long index)
 {
 	unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
-	void **entry = rcu_dereference_raw(parent->slots[offset]);
+	void *entry = rcu_dereference_raw(parent->slots[offset]);
 
 #ifdef CONFIG_RADIX_TREE_MULTIORDER
 	if (radix_tree_is_internal_node(entry)) {
-		unsigned long siboff = get_slot_offset(parent, entry);
+		unsigned long siboff = get_slot_offset(parent,
+						(void **)entry_to_node(entry));
 		if (siboff < RADIX_TREE_MAP_SIZE) {
 			offset = siboff;
 			entry = rcu_dereference_raw(parent->slots[offset]);
@@ -113,7 +120,7 @@ static unsigned int radix_tree_descend(struct radix_tree_node *parent,
 	}
 #endif
 
-	*nodep = (void *)entry;
+	*nodep = entry;
 	return offset;
 }
 
diff --git a/tools/testing/radix-tree/Makefile b/tools/testing/radix-tree/Makefile
index 3b53046..9d0919ed 100644
--- a/tools/testing/radix-tree/Makefile
+++ b/tools/testing/radix-tree/Makefile
@@ -1,5 +1,5 @@
 
-CFLAGS += -I. -g -Wall -D_LGPL_SOURCE
+CFLAGS += -I. -g -O2 -Wall -D_LGPL_SOURCE
 LDFLAGS += -lpthread -lurcu
 TARGETS = main
 OFILES = main.o radix-tree.o linux.o test.o tag_check.o find_next_bit.o \