diff --git a/src/write_dump.cpp b/src/write_dump.cpp
index 2ce28f01e4..98f7981f2e 100644
--- a/src/write_dump.cpp
+++ b/src/write_dump.cpp
@@ -49,8 +49,7 @@ void WriteDump::command(int narg, char **arg)
   dumpargs[0] = (char *) "WRITE_DUMP";    // dump id
   dumpargs[1] = arg[0];                   // group
   dumpargs[2] = arg[1];                   // dump style
-  std::string ntimestep = std::to_string(MAX(update->ntimestep, 1));
-  dumpargs[3] = (char *) ntimestep.c_str();    // dump frequency
+  dumpargs[3] = utils::strdup(std::to_string(MAX(update->ntimestep, 1)));   // dump frequency
 
   for (int i = 2; i < modindex; ++i) dumpargs[i + 2] = arg[i];
 
@@ -61,9 +60,7 @@ void WriteDump::command(int narg, char **arg)
   // set multifile_override for DumpImage so that filename needs no "*"
 
   if (strcmp(arg[1], "image") == 0) (dynamic_cast<DumpImage *>(dump))->multifile_override = 1;
-
   if (strcmp(arg[1], "cfg") == 0) (dynamic_cast<DumpCFG *>(dump))->multifile_override = 1;
-
   if ((update->first_update == 0) && (comm->me == 0))
     error->warning(FLERR, "Calling write_dump before a full system init.");
 
@@ -73,5 +70,6 @@ void WriteDump::command(int narg, char **arg)
   // delete the Dump instance and local storage
 
   output->delete_dump(dumpargs[0]);
+  delete[] dumpargs[3];
   delete[] dumpargs;
 }