diff --git a/complex.c b/complex.c
index 865466c499..d625ced7fa 100644
--- a/complex.c
+++ b/complex.c
@@ -2335,7 +2335,6 @@ Init_Complex(void)
     rb_undef_method(rb_cComplex, "%");
     rb_undef_method(rb_cComplex, "div");
     rb_undef_method(rb_cComplex, "divmod");
-    rb_undef_method(rb_cComplex, "ceildiv");
     rb_undef_method(rb_cComplex, "floor");
     rb_undef_method(rb_cComplex, "ceil");
     rb_undef_method(rb_cComplex, "modulo");
diff --git a/numeric.c b/numeric.c
index df0c016b9e..9574bfe024 100644
--- a/numeric.c
+++ b/numeric.c
@@ -656,31 +656,6 @@ num_div(VALUE x, VALUE y)
     return rb_funcall(num_funcall1(x, '/', y), rb_intern("floor"), 0);
 }
 
-/*
- *  call-seq:
- *    ceildiv(other) -> integer
- *
- *  Returns the quotient <tt>self/other</tt> as an integer, rounding up to the nearest integer.
- *  This method uses method +/+ in the derived class of +self+.
- *  (\Numeric itself does not define method +/+.)
- *
- *  Of the Core and Standard Library classes,
- *  Float and Rational use this implementation.
- *
- *    3.0.ceildiv(3.0) # => 1
- *    4.0.ceildiv(3.0) # => 2
- *
- *    4.0.ceildiv(-3.0) # => -1
- *    -4.0.ceildiv(3.0) # => -1
- *    -4.0.ceildiv(-3.0) # => 2
- */
-static VALUE
-num_ceildiv(VALUE x, VALUE y)
-{
-    VALUE tmp = num_div(x, num_uminus(y));
-    return num_uminus(tmp);
-}
-
 /*
  *  call-seq:
  *    self % other -> real_numeric
@@ -6247,7 +6222,6 @@ Init_Numeric(void)
     rb_define_method(rb_cNumeric, "<=>", num_cmp, 1);
     rb_define_method(rb_cNumeric, "eql?", num_eql, 1);
     rb_define_method(rb_cNumeric, "fdiv", num_fdiv, 1);
-    rb_define_method(rb_cNumeric, "ceildiv", num_ceildiv, 1);
     rb_define_method(rb_cNumeric, "div", num_div, 1);
     rb_define_method(rb_cNumeric, "divmod", num_divmod, 1);
     rb_define_method(rb_cNumeric, "%", num_modulo, 1);
diff --git a/test/ruby/test_complex.rb b/test/ruby/test_complex.rb
index 5cf52e812e..a3a7546575 100644
--- a/test/ruby/test_complex.rb
+++ b/test/ruby/test_complex.rb
@@ -915,7 +915,6 @@ class Complex_Test < Test::Unit::TestCase
     assert_not_respond_to(c, :%)
     assert_not_respond_to(c, :div)
     assert_not_respond_to(c, :divmod)
-    assert_not_respond_to(c, :ceildiv)
     assert_not_respond_to(c, :floor)
     assert_not_respond_to(c, :ceil)
     assert_not_respond_to(c, :modulo)
diff --git a/test/ruby/test_numeric.rb b/test/ruby/test_numeric.rb
index 068f9a56eb..0593cb535d 100644
--- a/test/ruby/test_numeric.rb
+++ b/test/ruby/test_numeric.rb
@@ -482,18 +482,4 @@ class TestNumeric < Test::Unit::TestCase
     assert_equal(0, -2.pow(3, 1))
   end
 
-  def test_ceildiv
-    assert_equal(0, 0.0.ceildiv(3.0))
-    assert_equal(1, 1.0.ceildiv(3.0))
-    assert_equal(1, 3.0.ceildiv(3.0))
-    assert_equal(2, 4.0.ceildiv(3.0))
-
-    assert_equal(-1, 4.0.ceildiv(-3.0))
-    assert_equal(-1, -4.0.ceildiv(3.0))
-    assert_equal(2, -4.0.ceildiv(-3.0))
-
-    assert_equal(3, 3.0.ceildiv(1.2))
-    assert_equal(3, 3.0.ceildiv(6/5r))
-    assert_equal(3, (7r/2).ceildiv(6/5r))
-  end
 end