diff --git a/Environment/ShowerAxis.cc b/Environment/ShowerAxis.cc
index 61412c48c689548f47583d92a181743647881c99..5b31178738807303a359be725df7958548bc488e 100644
--- a/Environment/ShowerAxis.cc
+++ b/Environment/ShowerAxis.cc
@@ -13,6 +13,7 @@
 
 using namespace corsika::environment;
 using namespace corsika::units::si;
+using namespace corsika;
 
 GrammageType ShowerAxis::X(LengthType l) const {
   auto const fractionalBin = l / steplength_;