diff --git a/shape.c b/shape.c
index 352c8d97a7..eee1b08bba 100644
--- a/shape.c
+++ b/shape.c
@@ -383,10 +383,7 @@ rb_shape_each_shape_id(each_shape_callback callback, void *data)
 RUBY_FUNC_EXPORTED rb_shape_t *
 rb_shape_lookup(shape_id_t shape_id)
 {
-    uint32_t offset = (shape_id & SHAPE_ID_OFFSET_MASK);
-    RUBY_ASSERT(offset != INVALID_SHAPE_ID);
-
-    return &GET_SHAPE_TREE()->shape_list[offset];
+    return RSHAPE(shape_id);
 }
 
 RUBY_FUNC_EXPORTED shape_id_t
diff --git a/shape.h b/shape.h
index ac50e58f71..392d3c9175 100644
--- a/shape.h
+++ b/shape.h
@@ -92,7 +92,10 @@ typedef struct {
     redblack_node_t *shape_cache;
     unsigned int cache_size;
 } rb_shape_tree_t;
+
+RUBY_SYMBOL_EXPORT_BEGIN
 RUBY_EXTERN rb_shape_tree_t *rb_shape_tree_ptr;
+RUBY_SYMBOL_EXPORT_END
 
 union rb_attr_index_cache {
     uint64_t pack;
@@ -149,7 +152,14 @@ RBASIC_SET_SHAPE_ID(VALUE obj, shape_id_t shape_id)
 #endif
 }
 
-#define RSHAPE rb_shape_lookup
+static inline rb_shape_t *
+RSHAPE(shape_id_t shape_id)
+{
+    uint32_t offset = (shape_id & SHAPE_ID_OFFSET_MASK);
+    RUBY_ASSERT(offset != INVALID_SHAPE_ID);
+
+    return &GET_SHAPE_TREE()->shape_list[offset];
+}
 
 int32_t rb_shape_id_offset(void);