diff --git a/src/scatter_buildblock/CreateTailMaskFromACFs.cxx b/src/scatter_buildblock/CreateTailMaskFromACFs.cxx
index 65a249dc0..884b83a5c 100644
--- a/src/scatter_buildblock/CreateTailMaskFromACFs.cxx
+++ b/src/scatter_buildblock/CreateTailMaskFromACFs.cxx
@@ -11,6 +11,7 @@
 #include "stir/scatter/CreateTailMaskFromACFs.h"
 #include "stir/Bin.h"
 #include "boost/lambda/lambda.hpp"
+#include "boost/format.hpp"
 #include "stir/error.h"
 
 START_NAMESPACE_STIR
@@ -147,8 +148,8 @@ CreateTailMaskFromACFs::process_data()
               count += mask_left_size + mask_right_size;
 #endif
             }
-          std::cout << count << " bins in mask for sinogram at segment " << bin.segment_num() << ", axial_pos "
-                    << bin.axial_pos_num() << "\n";
+          info(boost::format("%1% bins in mask for sinogram at segment %2%, axial_pos %3%") % count % bin.segment_num()
+               % bin.axial_pos_num());
           if (this->mask_proj_data->set_sinogram(mask_sinogram) != Succeeded::yes)
             return Succeeded::no;
         }