diff --git a/include/boost/ratio/ratio.hpp b/include/boost/ratio/ratio.hpp
index 9eef602..6278291 100644
--- a/include/boost/ratio/ratio.hpp
+++ b/include/boost/ratio/ratio.hpp
@@ -33,20 +33,17 @@ time2_demo contained this comment:
 #define BOOST_RATIO_RATIO_HPP
 
 #include <boost/ratio/ratio_fwd.hpp>
+#include <boost/ratio/detail/gcd_lcm.hpp>
 
 namespace boost
 {
 
-/*
-template <class R1, class R2>
-struct ratio_gcd :
-    ratio<mpl::gcd_c<boost::intmax_t, R1::num, R2::num>::value,
-        mpl::lcm_c<boost::intmax_t, R1::den, R2::den>::value>::type
+template <class R1, class R2> struct ratio_gcd: ratio<
+    ratio_detail::gcd<R1::num, R2::num>::value,
+    ratio_detail::lcm<R1::den, R2::den>::value>::type
 {
 };
-*/
 
 }  // namespace boost
 
-
 #endif  // BOOST_RATIO_RATIO_HPP
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 98b29c0..889d254 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -34,6 +34,7 @@ compile ratio_arithmetic/ratio_add_pass.cpp ;
 compile ratio_arithmetic/ratio_subtract_pass.cpp ;
 compile ratio_arithmetic/ratio_multiply_pass.cpp ;
 compile ratio_arithmetic/ratio_divide_pass.cpp ;
+compile ratio_arithmetic/ratio_gcd_pass.cpp ;
 compile-fail ratio_arithmetic/ratio_add_fail.cpp ;
 compile-fail ratio_arithmetic/ratio_add_2_fail.cpp ;
 #compile-fail ratio_arithmetic/ratio_add_3_fail.cpp ;
diff --git a/test/ratio_arithmetic/ratio_gcd_pass.cpp b/test/ratio_arithmetic/ratio_gcd_pass.cpp
new file mode 100644
index 0000000..2685183
--- /dev/null
+++ b/test/ratio_arithmetic/ratio_gcd_pass.cpp
@@ -0,0 +1,65 @@
+// Copyright 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/ratio/ratio.hpp>
+
+#define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
+
+void test()
+{
+    {
+    typedef boost::ratio<1, 1> R1;
+    typedef boost::ratio<1, 1> R2;
+    typedef boost::ratio_gcd<R1, R2> R;
+    STATIC_ASSERT(R::num == 1 && R::den == 1);
+    }
+    {
+    typedef boost::ratio<1, 2> R1;
+    typedef boost::ratio<1, 1> R2;
+    typedef boost::ratio_gcd<R1, R2> R;
+    STATIC_ASSERT(R::num == 1 && R::den == 2);
+    }
+    {
+    typedef boost::ratio<-1, 2> R1;
+    typedef boost::ratio<1, 1> R2;
+    typedef boost::ratio_gcd<R1, R2> R;
+    STATIC_ASSERT(R::num == 1 && R::den == 2);
+    }
+    {
+    typedef boost::ratio<1, -2> R1;
+    typedef boost::ratio<1, 1> R2;
+    typedef boost::ratio_gcd<R1, R2> R;
+    STATIC_ASSERT(R::num == 1 && R::den == 2);
+    }
+    {
+    typedef boost::ratio<1, 2> R1;
+    typedef boost::ratio<-1, 1> R2;
+    typedef boost::ratio_gcd<R1, R2> R;
+    STATIC_ASSERT(R::num == 1 && R::den == 2);
+    }
+    {
+    typedef boost::ratio<1, 2> R1;
+    typedef boost::ratio<1, -1> R2;
+    typedef boost::ratio_gcd<R1, R2> R;
+    STATIC_ASSERT(R::num == 1 && R::den == 2);
+    }
+    {
+    typedef boost::ratio<1, 2> R1;
+    typedef boost::ratio<1, 3> R2;
+    typedef boost::ratio_gcd<R1, R2> R;
+    STATIC_ASSERT(R::num == 1 && R::den == 6);
+    }
+    {
+    typedef boost::ratio<7, 13> R1;
+    typedef boost::ratio<11, 13> R2;
+    typedef boost::ratio_gcd<R1, R2> R;
+    STATIC_ASSERT(R::num == 1 && R::den == 13);
+    }
+    {
+    typedef boost::ratio<21, 55> R1;
+    typedef boost::ratio<14, 25> R2;
+    typedef boost::ratio_gcd<R1, R2> R;
+    STATIC_ASSERT(R::num == 7 && R::den == 275);
+    }
+}