diff --git a/include/boost/integer/common_factor_rt.hpp b/include/boost/integer/common_factor_rt.hpp
index b043e31..341b316 100644
--- a/include/boost/integer/common_factor_rt.hpp
+++ b/include/boost/integer/common_factor_rt.hpp
@@ -336,9 +336,9 @@ namespace boost {
 
       unsigned shifts = 0;
 
-      if(!u)
+      if(u == T(0))
          return v;
-      if(!v)
+      if(v == T(0))
          return u;
 
       shifts = constexpr_min(gcd_traits<T>::make_odd(u), gcd_traits<T>::make_odd(v));
@@ -347,9 +347,9 @@ namespace boost {
       {
          u %= v;
          v -= u;
-         if(!u)
+         if(u == T(0))
             return v << shifts;
-         if(!v)
+         if(v == T(0))
             return u << shifts;
          gcd_traits<T>::make_odd(u);
          gcd_traits<T>::make_odd(v);
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 691b703..23b3fe8 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -6,6 +6,9 @@ import testing ;
 
 project : requirements <warnings>all <toolset>gcc:<cxxflags>-Wextra ;
 
+obj has_gmpxx : has_gmpxx.cpp ;
+explicit has_gmpxx ;
+
 test-suite integer
     : 
         [ run integer_traits_test.cpp ]
@@ -28,5 +31,5 @@ test-suite integer
         [ compile-fail fail_uint_fast.cpp ]
         [ compile-fail fail_uint_least.cpp ]
         [ compile-fail fail_uint_65.cpp ]
-        [ run common_factor_test.cpp ]
+        [ run common_factor_test.cpp : : : [ check-target-builds "Checking for gmpxx.h" : <define>BOOST_INTEGER_HAS_GMPXX_H=1 ] ]
     ;
diff --git a/test/common_factor_test.cpp b/test/common_factor_test.cpp
index e071afe..0c36984 100644
--- a/test/common_factor_test.cpp
+++ b/test/common_factor_test.cpp
@@ -31,6 +31,10 @@
 #include <limits>   // for std::numeric_limits
 #include <ostream>  // for std::basic_ostream
 
+#ifdef BOOST_INTEGER_HAS_GMPXX_H
+#include <gmpxx.h>
+#endif
+
 
 namespace {
 
@@ -556,11 +560,11 @@ template <class T> void gcd_and_lcm_on_rationals()
     test<boost::multiprecision::int512_t>();
 
 #ifdef BOOST_HAS_LONG_LONG
-# define TEST_SIGNED( test ) \
+# define TEST_SIGNED__( test ) \
     TEST_SIGNED_( test ) \
     test<boost::long_long_type>();
 #elif defined(BOOST_HAS_MS_INT64)
-# define TEST_SIGNED( test ) \
+# define TEST_SIGNED__( test ) \
     TEST_SIGNED_( test ) \
     test<__int64>();
 #endif
@@ -584,6 +588,14 @@ template <class T> void gcd_and_lcm_on_rationals()
     test<unsigned __int64>();
 #endif
 
+#ifdef BOOST_INTEGER_HAS_GMPXX_H
+#  define TEST_SIGNED(test)\
+      TEST_SIGNED__(test)\
+      test<mpz_class>();
+#else
+#  define TEST_SIGNED(test) TEST_SIGNED__(test)
+#endif
+
 int main()
 {
    TEST_SIGNED(gcd_int_test)
diff --git a/test/has_gmpxx.cpp b/test/has_gmpxx.cpp
new file mode 100644
index 0000000..edf62d8
--- /dev/null
+++ b/test/has_gmpxx.cpp
@@ -0,0 +1,7 @@
+//  Copyright John Maddock 2008.
+//  Use, modification and distribution are subject to the
+//  Boost Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <gmpxx.h>
+