diff --git a/src/Classic/AbsBeamline/VerticalFFAMagnet.cpp b/src/Classic/AbsBeamline/VerticalFFAMagnet.cpp
index 60d62c89ab0ba3895bdd443838f7352d2d3612a2..b616b7396d0f857c7de8c3cc6455a131fa901f78 100644
--- a/src/Classic/AbsBeamline/VerticalFFAMagnet.cpp
+++ b/src/Classic/AbsBeamline/VerticalFFAMagnet.cpp
@@ -12,6 +12,8 @@
 
 #include "AbsBeamline/VerticalFFAMagnet.h"
 
+#include <cmath>
+
 VerticalFFAMagnet::VerticalFFAMagnet(const std::string &name)
         : Component(name), straightGeometry_m(1.) {
     setElType(isDrift);
@@ -79,7 +81,7 @@ void VerticalFFAMagnet::accept(BeamlineVisitor& visitor) const {
 
 
 bool VerticalFFAMagnet::getFieldValue(const Vector_t &R, Vector_t &B) const {
-    if (abs(R[0]) > halfWidth_m ||
+    if (std::abs(R[0]) > halfWidth_m ||
         R[2] < 0. || R[2] > bbLength_m ||
         R[1] < -zNegExtent_m || R[1] > zPosExtent_m) {
         return true;
diff --git a/tests/classic_src/AbsBeamline/VerticalFFAMagnetTest.cpp b/tests/classic_src/AbsBeamline/VerticalFFAMagnetTest.cpp
index 59a9149480dc2d36f25aae981edfca54e0373550..7e2ece9a606c4599118af4df8a562dcdd1938f00 100644
--- a/tests/classic_src/AbsBeamline/VerticalFFAMagnetTest.cpp
+++ b/tests/classic_src/AbsBeamline/VerticalFFAMagnetTest.cpp
@@ -132,7 +132,7 @@ TEST_F(VerticalFFAMagnetTest, MaxwellTest) {
         //maxTest.printLine(std::cerr, pos, 0.);
         double div = maxTest.divB(pos, 0.);
         double curl = euclidean_norm(maxTest.curlB(pos, 0.));
-        EXPECT_LT(abs(div), abs(divOld)) << i;
+        EXPECT_LT(std::abs(div), std::abs(divOld)) << i;
         EXPECT_LT(curl, 1e-11);
         std::cerr << "Max Order: " << i << " |curlB|: " << curl
                   << " DivB: " << div << std::endl;