diff --git a/include/boost/math/distributions/geometric.hpp b/include/boost/math/distributions/geometric.hpp
index baff0e249f..876d6a1761 100644
--- a/include/boost/math/distributions/geometric.hpp
+++ b/include/boost/math/distributions/geometric.hpp
@@ -401,7 +401,7 @@ namespace boost
       }
       if(k == 0)
       {
-        return log(p); // success_fraction
+        return std::log(p); // success_fraction
       }
       //RealType q = 1 - p;  // Bad for small p
       //RealType probability = 1 - std::pow(q, k+1);