diff --git a/include/boost/math/special_functions/next.hpp b/include/boost/math/special_functions/next.hpp
index 03715fc8f..42f7d8961 100644
--- a/include/boost/math/special_functions/next.hpp
+++ b/include/boost/math/special_functions/next.hpp
@@ -103,7 +103,7 @@ T float_next_imp(const T& val, const Policy& pol)
 
    int fpclass = (boost::math::fpclassify)(val);
 
-   if((fpclass == FP_NAN) || (fpclass == FP_INFINITE))
+   if((fpclass == (int)FP_NAN) || (fpclass == (int)FP_INFINITE))
    {
       if(val < 0)
          return -tools::max_value<T>();
@@ -118,7 +118,7 @@ T float_next_imp(const T& val, const Policy& pol)
    if(val == 0)
       return detail::get_smallest_value<T>();
 
-   if((fpclass != FP_SUBNORMAL) && (fpclass != FP_ZERO) && (fabs(val) < detail::get_min_shift_value<T>()) && (val != -tools::min_value<T>()))
+   if((fpclass != (int)FP_SUBNORMAL) && (fpclass != (int)FP_ZERO) && (fabs(val) < detail::get_min_shift_value<T>()) && (val != -tools::min_value<T>()))
    {
       //
       // Special case: if the value of the least significant bit is a denorm, and the result
@@ -185,7 +185,7 @@ T float_prior_imp(const T& val, const Policy& pol)
 
    int fpclass = (boost::math::fpclassify)(val);
 
-   if((fpclass == FP_NAN) || (fpclass == FP_INFINITE))
+   if((fpclass == (int)FP_NAN) || (fpclass == (int)FP_INFINITE))
    {
       if(val > 0)
          return tools::max_value<T>();
@@ -200,7 +200,7 @@ T float_prior_imp(const T& val, const Policy& pol)
    if(val == 0)
       return -detail::get_smallest_value<T>();
 
-   if((fpclass != FP_SUBNORMAL) && (fpclass != FP_ZERO) && (fabs(val) < detail::get_min_shift_value<T>()) && (val != tools::min_value<T>()))
+   if((fpclass != (int)FP_SUBNORMAL) && (fpclass != (int)FP_ZERO) && (fabs(val) < detail::get_min_shift_value<T>()) && (val != tools::min_value<T>()))
    {
       //
       // Special case: if the value of the least significant bit is a denorm, and the result
@@ -318,7 +318,7 @@ T float_distance_imp(const T& a, const T& b, const Policy& pol)
    // because we actually have fewer than tools::digits<T>()
    // significant bits in the representation:
    //
-   frexp(((boost::math::fpclassify)(a) == FP_SUBNORMAL) ? tools::min_value<T>() : a, &expon);
+   frexp(((boost::math::fpclassify)(a) == (int)FP_SUBNORMAL) ? tools::min_value<T>() : a, &expon);
    T upper = ldexp(T(1), expon);
    T result = 0;
    expon = tools::digits<T>() - expon;
@@ -335,7 +335,7 @@ T float_distance_imp(const T& a, const T& b, const Policy& pol)
    // errors in the subtraction:
    //
    T mb, x, y, z;
-   if(((boost::math::fpclassify)(a) == FP_SUBNORMAL) || (b - a < tools::min_value<T>()))
+   if(((boost::math::fpclassify)(a) == (int)FP_SUBNORMAL) || (b - a < tools::min_value<T>()))
    {
       //
       // Special case - either one end of the range is a denormal, or else the difference is.
@@ -399,7 +399,7 @@ T float_advance_imp(T val, int distance, const Policy& pol)
 
    int fpclass = (boost::math::fpclassify)(val);
 
-   if((fpclass == FP_NAN) || (fpclass == FP_INFINITE))
+   if((fpclass == (int)FP_NAN) || (fpclass == (int)FP_INFINITE))
       return policies::raise_domain_error<T>(
          function,
          "Argument val must be finite, but got %1%", val, pol);