diff --git a/srsue/test/ttcn3/hdr/ttcn3_drb_interface.h b/srsue/test/ttcn3/hdr/ttcn3_drb_interface.h
index bebec5126..f3b21f24d 100644
--- a/srsue/test/ttcn3/hdr/ttcn3_drb_interface.h
+++ b/srsue/test/ttcn3/hdr/ttcn3_drb_interface.h
@@ -50,12 +50,11 @@ public:
     return port_listen();
   }
 
-  void tx(std::string out)
+  void tx(const uint8_t* buffer, uint32_t len)
   {
     if (initialized) {
-      log->info_hex(
-          reinterpret_cast<const uint8_t*>(out.c_str()), out.length(), "Sending %ld B to Titan\n", out.length());
-      send(reinterpret_cast<const uint8_t*>(out.c_str()), out.length());
+      log->info_hex(buffer, len, "Sending %d B to Titan\n", len);
+      send(buffer, len);
     } else {
       log->error("Trying to transmit but port not connected.\n");
     }
diff --git a/srsue/test/ttcn3/src/ttcn3_syssim.cc b/srsue/test/ttcn3/src/ttcn3_syssim.cc
index 059b638d9..720a4b260 100644
--- a/srsue/test/ttcn3/src/ttcn3_syssim.cc
+++ b/srsue/test/ttcn3/src/ttcn3_syssim.cc
@@ -1045,7 +1045,7 @@ void ttcn3_syssim::write_pdu(uint32_t lcid, unique_byte_buffer_t pdu)
   } else {
     std::string out = ttcn3_helpers::get_drb_common_ind_for_pdu(tti, lcid, cells[pcell_idx]->name, std::move(pdu));
     log->error("DRB send:\n%s", out.c_str());
-    drb.tx(out);
+    drb.tx(reinterpret_cast<const uint8_t*>(out.c_str()), out.length());
   }
 }