diff --git a/include/boost/math/special_functions/fpclassify.hpp b/include/boost/math/special_functions/fpclassify.hpp
index 51723787b..f8a3c3e94 100644
--- a/include/boost/math/special_functions/fpclassify.hpp
+++ b/include/boost/math/special_functions/fpclassify.hpp
@@ -73,7 +73,7 @@ inline bool is_nan_helper(T t, const boost::true_type&)
 #ifdef isnan
    return isnan(t);
 #else // BOOST_HAS_FPCLASSIFY
-   return (BOOST_FPCLASSIFY_PREFIX fpclassify(t) == FP_NAN);
+   return (BOOST_FPCLASSIFY_PREFIX fpclassify(t) == (int)FP_NAN);
 #endif
 }
 
@@ -200,19 +200,19 @@ template <class T>
 inline bool isfinite BOOST_NO_MACRO_EXPAND(T z)
 {
    int t = (::boost::math::fpclassify)(z);
-   return (t != FP_NAN) && (t != FP_INFINITE);
+   return (t != (int)FP_NAN) && (t != (int)FP_INFINITE);
 }
 
 template <class T>
 inline bool isinf BOOST_NO_MACRO_EXPAND(T t)
 {
-   return (::boost::math::fpclassify)(t) == FP_INFINITE;
+   return (::boost::math::fpclassify)(t) == (int)FP_INFINITE;
 }
 
 template <class T>
 inline bool isnan BOOST_NO_MACRO_EXPAND(T t)
 {
-   return (::boost::math::fpclassify)(t) == FP_NAN;
+   return (::boost::math::fpclassify)(t) == (int)FP_NAN;
 }
 #ifdef isnan
 template <> inline bool isnan BOOST_NO_MACRO_EXPAND<float>(float t){ return ::boost::math_detail::is_nan_helper(t, boost::true_type()); }
@@ -232,7 +232,7 @@ template <> inline bool isnan BOOST_NO_MACRO_EXPAND<long double>(long double t){
 template <class T>
 inline bool isnormal BOOST_NO_MACRO_EXPAND(T t)
 {
-   return (::boost::math::fpclassify)(t) == FP_NORMAL;
+   return (::boost::math::fpclassify)(t) == (int)FP_NORMAL;
 }
 
 } // namespace math
diff --git a/include/boost/math/special_functions/gamma.hpp b/include/boost/math/special_functions/gamma.hpp
index 0a0ed8f2b..1d02a3ddb 100644
--- a/include/boost/math/special_functions/gamma.hpp
+++ b/include/boost/math/special_functions/gamma.hpp
@@ -152,7 +152,7 @@ T gamma_imp(T z, const Policy& pol, const L& l)
       result = -boost::math::constants::pi<T>() / result;
       if(result == 0)
          return policies::raise_underflow_error<T>(function, "Result of tgamma is too small to represent.", pol);
-      if((boost::math::fpclassify)(result) == FP_SUBNORMAL)
+      if((boost::math::fpclassify)(result) == (int)FP_SUBNORMAL)
          return policies::raise_denorm_error<T>(function, "Result of tgamma is denormalized.", result, pol);
       return result;
    }
@@ -352,7 +352,7 @@ T gamma_imp(T z, const Policy& pol, const lanczos::undefined_lanczos& l)
       result = -boost::math::constants::pi<T>() / result;
       if(result == 0)
          return policies::raise_underflow_error<T>(function, "Result of tgamma is too small to represent.", pol);
-      if((boost::math::fpclassify)(result) == FP_SUBNORMAL)
+      if((boost::math::fpclassify)(result) == (int)FP_SUBNORMAL)
          return policies::raise_denorm_error<T>(function, "Result of tgamma is denormalized.", result, pol);
       return result;
    }
@@ -584,7 +584,7 @@ T full_igamma_prefix(T a, T z, const Policy& pol)
    // This error handling isn't very good: it happens after the fact
    // rather than before it...
    //
-   if((boost::math::fpclassify)(prefix) == FP_INFINITE)
+   if((boost::math::fpclassify)(prefix) == (int)FP_INFINITE)
       policies::raise_overflow_error<T>("boost::math::detail::full_igamma_prefix<%1%>(%1%, %1%)", "Result of incomplete gamma function is too large to represent.", pol);
 
    return prefix;