diff --git a/src/USER-MANIFOLD/manifold_gaussian_bump.cpp b/src/USER-MANIFOLD/manifold_gaussian_bump.cpp
index e1a3deb5ab7a8440085233b78da7a3643a3183aa..db8c589afb092feb0e3d1b853e034618317e7fb8 100644
--- a/src/USER-MANIFOLD/manifold_gaussian_bump.cpp
+++ b/src/USER-MANIFOLD/manifold_gaussian_bump.cpp
@@ -72,7 +72,7 @@ public:
       ff  = x(t) - xx;
       ffp = xp(t);
       double res = ff;
-      if( std::fabs( res ) < tol ){
+      if( fabs( res ) < tol ){
         return t;
       }
     }