diff --git a/numeric.c b/numeric.c
index a7769ca255..17b6b92982 100644
--- a/numeric.c
+++ b/numeric.c
@@ -5241,6 +5241,44 @@ rb_int_s_isqrt(VALUE self, VALUE num)
     }
 }
 
+static VALUE
+rb_int_s_from_digits(int argc, VALUE *argv, VALUE klass) {
+    VALUE digits, base, array;
+    long size, levels, level;
+    rb_check_arity(argc, 1, 2);
+    digits = rb_to_array_type(argv[0]);
+    base = argc == 2 ? rb_to_int(argv[1]) : INT2FIX(10);
+    if (FIXNUM_P(base) && FIX2LONG(base) < 2)
+	rb_raise(rb_eArgError, "invalid radix %ld", FIX2LONG(base));
+    else if (RB_TYPE_P(base, T_BIGNUM) && BIGNUM_NEGATIVE_P(base))
+	rb_raise(rb_eArgError, "negative radix");
+    array = rb_ary_dup(digits);
+    size = RARRAY_LEN(array);
+    levels = bit_length(size);
+    for (level = 0; level < levels; level++) {
+	long stride = 2 << level;
+	long i, n = (size + stride - 1) / stride;
+	if (level) base = rb_int_mul(base, base);
+	for (i = 0; i < n; i++) {
+	    VALUE div = INT2FIX(0);
+	    VALUE mod = rb_to_int(RARRAY_AREF(array, 2 * i));
+	    RARRAY_ASET(array, 2 * i, INT2FIX(0));
+	    if (2 * i + 1 < size) {
+		div = rb_to_int(RARRAY_AREF(array, 2 * i + 1));
+		RARRAY_ASET(array, 2 * i + 1, INT2FIX(0));
+	    }
+	    if (div == INT2FIX(0)) {
+		RARRAY_ASET(array, i, mod);
+	    } else {
+		div = rb_to_int(div);
+		RARRAY_ASET(array, i, rb_int_plus(rb_int_mul(div, base), mod));
+	    }
+	}
+    }
+    return RARRAY_AREF(array, 0);
+}
+
+
 /*
  *  Document-class: ZeroDivisionError
  *
@@ -5393,6 +5431,7 @@ Init_Numeric(void)
     rb_undef_alloc_func(rb_cInteger);
     rb_undef_method(CLASS_OF(rb_cInteger), "new");
     rb_define_singleton_method(rb_cInteger, "sqrt", rb_int_s_isqrt, 1);
+    rb_define_singleton_method(rb_cInteger, "from_digits", rb_int_s_from_digits, -1);
 
     rb_define_method(rb_cInteger, "to_s", int_to_s, -1);
     rb_define_alias(rb_cInteger, "inspect", "to_s");
diff --git a/test/ruby/test_integer.rb b/test/ruby/test_integer.rb
index 1b485760e3..c8c84c28c2 100644
--- a/test/ruby/test_integer.rb
+++ b/test/ruby/test_integer.rb
@@ -477,6 +477,21 @@ def to_int
     assert_equal([0, 1], 10.digits(o))
   end
 
+  def test_from_digits
+    assert_equal(Integer.from_digits([0]), 0)
+    assert_equal(Integer.from_digits([1]), 1)
+    assert_equal(Integer.from_digits([4, 3, 2, 1]), 1234)
+    assert_equal(Integer.from_digits([1, 0, 1, 1, 1], 2), 29)
+    assert_equal(Integer.from_digits((9**999).digits), 9**999)
+    assert_equal(Integer.from_digits([1, 1, 1], 1 << 128), (1 << 256) | (1 << 128) | 1)
+    assert_raise(TypeError) { Integer.from_digits("4321") }
+    assert_raise(TypeError) { Integer.from_digits([4, 3, 2, 1], "10") }
+    assert_raise(TypeError) { Integer.from_digits([4, "3", 2, 1]) }
+    assert_raise(ArgumentError) { Integer.from_digits([4, 3, 2, 1], 1) }
+    assert_raise(ArgumentError) { Integer.from_digits([4, 3, 2, 1], 0) }
+    assert_raise(ArgumentError) { Integer.from_digits([4, 3, 2, 1], -9**999) }
+  end
+
   def test_square_root
     assert_raise(TypeError) {Integer.sqrt("x")}
     assert_raise(Math::DomainError) {Integer.sqrt(-1)}