diff --git a/DDG4/src/Geant4SensDetAction.cpp b/DDG4/src/Geant4SensDetAction.cpp
index 465ca0e141c094beaef2a14de43be8b5fed82a13..3de8ab5ea88c3ec3582737bd74df303f10cabc68 100644
--- a/DDG4/src/Geant4SensDetAction.cpp
+++ b/DDG4/src/Geant4SensDetAction.cpp
@@ -279,9 +279,9 @@ long long int Geant4Sensitive::cellID(const G4Step* step) {
       error("....... TGeo-local: (%f, %f, %f) TGeo-global: (%f, %f, %f)",
 	    loc.x(), loc.y(), loc.z(), glob.x(), glob.y(), glob.z());
       if ( h.pre )
-	error("....... Pre-step:  %s  SD: %s", h.volName(h.pre), h.sdName(h.pre));
+        error("....... Pre-step:  %s  SD: %s", h.volName(h.pre), h.sdName(h.pre).c_str());
       if ( h.post )
-	error("....... Post-step: %s  SD: %s", h.volName(h.post), h.sdName(h.post));
+	error("....... Post-step: %s  SD: %s", h.volName(h.post), h.sdName(h.post).c_str());
       std::rethrow_exception(eptr);
     }
   }