diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 3db9c6478..e8569b654 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -21,7 +21,7 @@
 #include <regex>
 #include <dlfcn.h>
 
-#include <math.h>
+#include <cmath>
 
 
 namespace nix {