diff --git a/unsupported/test/NonLinearOptimization.cpp b/unsupported/test/NonLinearOptimization.cpp
index 6a5ed057f..1d682dd83 100644
--- a/unsupported/test/NonLinearOptimization.cpp
+++ b/unsupported/test/NonLinearOptimization.cpp
@@ -12,8 +12,6 @@
 // It is intended to be done for this test only.
 #include <Eigen/src/Core/util/DisableStupidWarnings.h>
 
-using std::sqrt;
-
 // tolerance for chekcing number of iterations
 #define LM_EVAL_COUNT_TOL 4/3