diff --git a/src/min_hftn.cpp b/src/min_hftn.cpp
index 19adb345c0..5db8c0e98d 100644
--- a/src/min_hftn.cpp
+++ b/src/min_hftn.cpp
@@ -1598,14 +1598,9 @@ void MinHFTN::open_hftn_print_file_()
   int  nMyRank;
   MPI_Comm_rank (world, &nMyRank);
 
-  char  szTmp[50];
-  sprintf (szTmp, "progress_MinHFTN_%d.txt", nMyRank);
-  _fpPrint = fopen (szTmp, "w");
-  if (_fpPrint == nullptr) {
-    printf ("*** MinHFTN cannot open file '%s'\n", szTmp);
-    printf ("*** continuing...\n");
-    return;
-  }
+  auto szTmp = fmt::format("progress_MinHFTN_{}.txt", nMyRank);
+  _fpPrint = fopen (szTmp.c_str(), "w");
+  if (_fpPrint == nullptr) return;
 
   fprintf (_fpPrint, "  Iter   Evals      Energy         |F|_2"
            "    Step   TR used    |step|_2      ared      pred\n");