diff --git a/scram-tools.file/tools/geant4/env.sh b/scram-tools.file/tools/geant4/env.sh
index adc8738b9b8..883117ebdf9 100644
--- a/scram-tools.file/tools/geant4/env.sh
+++ b/scram-tools.file/tools/geant4/env.sh
@@ -1,6 +1,6 @@
 GEANT4_VECGEOM=""
 if grep VECGEOM_ROOT ${TOOL_ROOT}/etc/profile.d/dependencies-setup.sh >/dev/null 2>&1  ; then
-  GEANT4_VECGEOM='<use name="vecgeom"/>'
+  GEANT4_VECGEOM='<use name="vecgeom"/><flags CXXFLAGS="-DG4GEOM_USE_USOLIDS"/>'
 fi
 export GEANT4_VECGEOM