diff --git a/src/math.hpp b/src/math.hpp
index d936824966c59d18758f232bd4b351ce77cdeca1..5c3a00b4af2e54f388b40089a23486ae6e5c4a10 100644
--- a/src/math.hpp
+++ b/src/math.hpp
@@ -13,7 +13,7 @@ namespace nestmc {
     T area_frustrum(T L, T r1, T r2)
     {
         auto dr = r1 - r2;
-        return pi<double>() * (r1+r2) * sqrt(L*L + dr*dr);
+        return pi<double>() * (r1+r2) * std::sqrt(L*L + dr*dr);
     }
 
     template <typename T>
diff --git a/tests/test_point.cpp b/tests/test_point.cpp
index 9fbb62a2fd6819caf1e1b97a2c62013d98886f24..f2499d427fb56217ec98ff8694a446d4a4903229 100644
--- a/tests/test_point.cpp
+++ b/tests/test_point.cpp
@@ -1,4 +1,5 @@
 #include <limits>
+#include <cmath>
 
 #include "gtest.h"
 
@@ -97,8 +98,8 @@ TEST(point, norm)
     point<double> p1(1, 1, 1);
     point<double> p2(1, 2, 3);
 
-    EXPECT_EQ(norm(p1), sqrt(3.));
-    EXPECT_EQ(norm(p2), sqrt(1.+4.+9.));
+    EXPECT_EQ(norm(p1), std::sqrt(3.));
+    EXPECT_EQ(norm(p2), std::sqrt(1.+4.+9.));
 }
 
 TEST(point, dot)