diff --git a/shape.c b/shape.c
index 5a4a271b30..de57551fcf 100644
--- a/shape.c
+++ b/shape.c
@@ -1057,6 +1057,15 @@ rb_shape_shapes_available(VALUE self)
     return INT2NUM(MAX_SHAPE_ID - (GET_SHAPE_TREE()->next_shape_id - 1));
 }
 
+static VALUE
+rb_shape_exhaust(int argc, VALUE *argv, VALUE self)
+{
+    rb_check_arity(argc, 0, 1);
+    int offset = argc == 1 ? NUM2INT(argv[0]) : 0;
+    GET_SHAPE_TREE()->next_shape_id = MAX_SHAPE_ID - offset;
+    return Qnil;
+}
+
 VALUE rb_obj_shape(rb_shape_t* shape);
 
 static enum rb_id_table_iterator_result collect_keys_and_values(ID key, VALUE value, void *ref)
@@ -1239,5 +1248,6 @@ Init_shape(void)
     rb_define_singleton_method(rb_cShape, "of", rb_shape_debug_shape, 1);
     rb_define_singleton_method(rb_cShape, "root_shape", rb_shape_root_shape, 0);
     rb_define_singleton_method(rb_cShape, "shapes_available", rb_shape_shapes_available, 0);
+    rb_define_singleton_method(rb_cShape, "exhaust_shapes", rb_shape_exhaust, -1);
 #endif
 }
diff --git a/test/ruby/test_shapes.rb b/test/ruby/test_shapes.rb
index 57c97d9031..cf1885bbdf 100644
--- a/test/ruby/test_shapes.rb
+++ b/test/ruby/test_shapes.rb
@@ -191,12 +191,7 @@ class TestShapes < Test::Unit::TestCase
         attr_reader :very_unique
       end
 
-      obj = Object.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 0
-        obj.instance_variable_set(:"@a#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       (RubyVM::Shape::SHAPE_MAX_VARIATIONS * 2).times do
         TooComplex.new.instance_variable_set(:"@unique_#{_1}", 1)
@@ -216,13 +211,7 @@ class TestShapes < Test::Unit::TestCase
     assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
     begin;
       class Hi; end
-
-      obj = Hi.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 2
-        obj.instance_variable_set(:"@a#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes(3)
 
       obj = Hi.new
       i = 0
@@ -243,26 +232,16 @@ class TestShapes < Test::Unit::TestCase
           @a = 1
         end
       end
-      # Try to run out of shapes
-      o = Object.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 0
-        o.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-        A.new
-      end
+      RubyVM::Shape.exhaust_shapes
+
+      A.new
     end;
   end
 
   def test_run_out_of_shape_for_class_ivar
     assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
     begin;
-      i = 0
-      while RubyVM::Shape.shapes_available > 0
-        c = Class.new
-        c.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       c = Class.new
       c.instance_variable_set(:@a, 1)
@@ -282,12 +261,7 @@ class TestShapes < Test::Unit::TestCase
     begin;
       [].instance_variable_set(:@a, 1)
 
-      i = 0
-      o = Object.new
-      while RubyVM::Shape.shapes_available > 0
-        o.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       ary = 10.times.map { [] }
 
@@ -302,12 +276,7 @@ class TestShapes < Test::Unit::TestCase
   def test_run_out_of_shape_for_module_ivar
     assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
     begin;
-      o = Object.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 0
-        o.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       module Foo
         @a = 1
@@ -321,12 +290,7 @@ class TestShapes < Test::Unit::TestCase
   def test_run_out_of_shape_for_class_cvar
     assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
     begin;
-      i = 0
-      while RubyVM::Shape.shapes_available > 0
-        c = Class.new
-        c.class_variable_set(:"@@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       c = Class.new
 
@@ -348,13 +312,7 @@ class TestShapes < Test::Unit::TestCase
       class TooComplex < Hash
       end
 
-      # Try to run out of shapes
-      o = Object.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 0
-        o.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       tc = TooComplex.new
       tc.instance_variable_set(:@a, 1)
@@ -387,15 +345,10 @@ class TestShapes < Test::Unit::TestCase
       a = Hi.new
 
       # Try to run out of shapes
-      o = Object.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 0
-        o.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
-      assert_equal 1,a.transition
-      assert_equal 1,a.transition
+      assert_equal 1, a.transition
+      assert_equal 1, a.transition
     end;
   end
 
@@ -409,12 +362,7 @@ class TestShapes < Test::Unit::TestCase
         end
       end
 
-      o = Object.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 0
-        o.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       a = A.new
       assert_equal true, a.instance_variable_defined?(:@a)
@@ -424,12 +372,7 @@ class TestShapes < Test::Unit::TestCase
   def test_run_out_of_shape_instance_variable_defined_on_module
     assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
     begin;
-      o = Object.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 0
-        o.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       module A
         @a = @b = @c = @d = 1
@@ -445,12 +388,7 @@ class TestShapes < Test::Unit::TestCase
       o = Object.new
       10.times { |i| o.instance_variable_set(:"@a#{i}", i) }
 
-      i = 0
-      a = Object.new
-      while RubyVM::Shape.shapes_available > 2
-        a.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       o.remove_instance_variable(:@a0)
       (1...10).each do |i|
@@ -471,12 +409,7 @@ class TestShapes < Test::Unit::TestCase
 
       a = A.new
 
-      o = Object.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 0
-        o.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       a.remove_instance_variable(:@b)
       assert_nil a.b
@@ -506,12 +439,7 @@ class TestShapes < Test::Unit::TestCase
 
       a = A.new
 
-      o = Object.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 1
-        o.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       a.dup
     end;
@@ -522,12 +450,7 @@ class TestShapes < Test::Unit::TestCase
       o = []
       o.instance_variable_set(:@a, 1)
 
-      i = 0
-      o = Object.new
-      while RubyVM::Shape.shapes_available > 0
-        o.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       ary = 1_000_000.times.map { [] }
     begin;
@@ -546,12 +469,7 @@ class TestShapes < Test::Unit::TestCase
     begin;
       class Hi; end
 
-      obj = Hi.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 2
-        obj.instance_variable_set(:"@a#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes(2)
 
       obj = Module.new
       3.times do
@@ -571,12 +489,7 @@ class TestShapes < Test::Unit::TestCase
     begin;
       class Hi; end
 
-      obj = Hi.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 2
-        obj.instance_variable_set(:"@a#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes(2)
 
       obj = Object.new
       i = 0
@@ -748,12 +661,7 @@ class TestShapes < Test::Unit::TestCase
       end
       assert_equal [0, 1, 2, 3, 4], ivars
 
-      o = Object.new
-      i = 0
-      while RubyVM::Shape.shapes_available > 0
-        o.instance_variable_set(:"@i#{i}", 1)
-        i += 1
-      end
+      RubyVM::Shape.exhaust_shapes
 
       object.remove_instance_variable(:@ivar_2)