diff --git a/sample/CMakeLists.txt b/sample/CMakeLists.txt
index 1e6a3ac..db9ac43 100644
--- a/sample/CMakeLists.txt
+++ b/sample/CMakeLists.txt
@@ -18,3 +18,6 @@ target_link_libraries(testkd2 ${tolink})
 
 add_executable(testDelaunay testDelaunay.cpp)
 target_link_libraries(testDelaunay ${tolink})
+
+add_executable(testNewton testNewton.cpp)
+target_link_libraries(testNewton ${tolink})
\ No newline at end of file
diff --git a/src/newton.hpp b/src/newton.hpp
index ca39804..3e861f0 100644
--- a/src/newton.hpp
+++ b/src/newton.hpp
@@ -1,6 +1,8 @@
 #ifndef _COSMOTOOL_NEWTON_HPP
 #define _COSMOTOOL_NEWTON_HPP
 
+#include <cmath>
+
 namespace CosmoTool
 {
   template<typename T, typename FunT>
@@ -12,7 +14,7 @@ namespace CosmoTool
     
     x = xold - f_x/df_x;
 
-    while (abs(xold-x) > residual)
+    while (std::abs(xold-x) > residual)
       {	
 	xold = x;
 	f_x = function.eval(x);