diff --git a/include/internal/catch_approx.hpp b/include/internal/catch_approx.hpp
index f5dba61a..f5eacbd0 100644
--- a/include/internal/catch_approx.hpp
+++ b/include/internal/catch_approx.hpp
@@ -43,7 +43,7 @@ namespace Detail {
 
         friend bool operator == ( double lhs, Approx const& rhs ) {
             // Thanks to Richard Harris for his help refining this formula
-            return fabs( lhs - rhs.m_value ) < rhs.m_epsilon * (rhs.m_scale + (std::max)( fabs(lhs), fabs(rhs.m_value) ) );
+            return std::fabs( lhs - rhs.m_value ) < rhs.m_epsilon * (rhs.m_scale + (std::max)( std::fabs(lhs), std::fabs(rhs.m_value) ) );
         }
 
         friend bool operator == ( Approx const& lhs, double rhs ) {