diff --git a/shape.h b/shape.h
index 9a84835e65..9f0d5e8b14 100644
--- a/shape.h
+++ b/shape.h
@@ -150,16 +150,10 @@ rb_obj_shape(VALUE obj)
     return RSHAPE(rb_obj_shape_id(obj));
 }
 
-static inline bool
-rb_shape_canonical_p(rb_shape_t *shape)
-{
-    return !shape->flags;
-}
-
 static inline bool
 rb_shape_id_canonical_p(shape_id_t shape_id)
 {
-    return rb_shape_canonical_p(RSHAPE(shape_id));
+    return !RSHAPE(shape_id)->flags;
 }
 
 static inline shape_id_t
diff --git a/variable.c b/variable.c
index 1f948fb356..e8aedc5ac0 100644
--- a/variable.c
+++ b/variable.c
@@ -1663,7 +1663,7 @@ rb_obj_init_too_complex(VALUE obj, st_table *table)
 {
     // This method is meant to be called on newly allocated object.
     RUBY_ASSERT(!rb_shape_obj_too_complex_p(obj));
-    RUBY_ASSERT(rb_shape_canonical_p(rb_obj_shape(obj)));
+    RUBY_ASSERT(rb_shape_id_canonical_p(RBASIC_SHAPE_ID(obj)));
     RUBY_ASSERT(rb_obj_shape(obj)->next_field_index == 0);
 
     obj_transition_too_complex(obj, table);