diff --git a/src/MACHDYN/fix_smd_adjust_dt.cpp b/src/MACHDYN/fix_smd_adjust_dt.cpp
index 6f7539b476..d2728f1042 100644
--- a/src/MACHDYN/fix_smd_adjust_dt.cpp
+++ b/src/MACHDYN/fix_smd_adjust_dt.cpp
@@ -43,8 +43,7 @@ using namespace FixConst;
 
 FixSMDTlsphDtReset::FixSMDTlsphDtReset(LAMMPS *lmp, int narg, char **arg) :
                 Fix(lmp, narg, arg) {
-        if (narg != 4)
-                error->all(FLERR, "Illegal fix smd/adjust_dt command");
+        if (narg != 4) error->all(FLERR, "Illegal fix smd/adjust_dt command");
 
         // set time_depend, else elapsed time accumulation can be messed up
 
@@ -57,7 +56,7 @@ FixSMDTlsphDtReset::FixSMDTlsphDtReset(LAMMPS *lmp, int narg, char **arg) :
         extvector = 0;
         restart_global = 1; // this fix stores global (i.e., not per-atom) info: elaspsed time
 
-        safety_factor = atof(arg[3]);
+        safety_factor = utils::numeric(FLERR,arg[3],false,lmp);
 
         // initializations
         t_elapsed = 0.0;
diff --git a/src/MACHDYN/pair_smd_hertz.cpp b/src/MACHDYN/pair_smd_hertz.cpp
index 7c9eac217f..bf526f5e4e 100644
--- a/src/MACHDYN/pair_smd_hertz.cpp
+++ b/src/MACHDYN/pair_smd_hertz.cpp
@@ -263,7 +263,7 @@ void PairHertz::coeff(int narg, char **arg) {
         utils::bounds(FLERR,arg[0], 1, atom->ntypes, ilo, ihi, error);
         utils::bounds(FLERR,arg[1], 1, atom->ntypes, jlo, jhi, error);
 
-        double bulkmodulus_one = atof(arg[2]);
+        double bulkmodulus_one = utils::numeric(FLERR,arg[2],false,lmp);
 
         // set short-range force constant
         double kn_one = 0.0;
diff --git a/src/MACHDYN/pair_smd_triangulated_surface.cpp b/src/MACHDYN/pair_smd_triangulated_surface.cpp
index fbd2c14aa6..e1ebc2562d 100644
--- a/src/MACHDYN/pair_smd_triangulated_surface.cpp
+++ b/src/MACHDYN/pair_smd_triangulated_surface.cpp
@@ -345,7 +345,7 @@ void PairTriSurf::coeff(int narg, char **arg) {
         utils::bounds(FLERR,arg[0], 1,atom->ntypes, ilo, ihi, error);
         utils::bounds(FLERR,arg[1], 1,atom->ntypes, jlo, jhi, error);
 
-        double bulkmodulus_one = atof(arg[2]);
+        double bulkmodulus_one = utils::numeric(FLERR,arg[2],false,lmp);
 
         // set short-range force constant
         double kn_one = 0.0;
diff --git a/src/QTB/fix_qbmsst.cpp b/src/QTB/fix_qbmsst.cpp
index 839e08662c..b5fb5ca77c 100644
--- a/src/QTB/fix_qbmsst.cpp
+++ b/src/QTB/fix_qbmsst.cpp
@@ -45,7 +45,7 @@ using namespace MathConst;
 
 FixQBMSST::FixQBMSST(LAMMPS *lmp, int narg, char **arg) : Fix(lmp, narg, arg)
 {
-  if (narg < 5) error->all(FLERR,"Illegal fix qbmsst command");
+  if (narg < 5) utils::missing_cmd_args(FLERR,"fix qbmsst",error);
 
   if (strcmp(arg[3],"x") == 0) {
     direction = 0;
@@ -57,11 +57,10 @@ FixQBMSST::FixQBMSST(LAMMPS *lmp, int narg, char **arg) : Fix(lmp, narg, arg)
     direction = 2;
     box_change |= BOX_CHANGE_Z;
   } else {
-    error->all(FLERR,"Illegal fix qbmsst command");
+    error->all(FLERR,"Unknown fix qbmsst direction keyword: {}", arg[3]);
   }
-  velocity = atof(arg[4]);
-  if (velocity < 0)
-    error->all(FLERR,"Illegal fix qbmsst command");
+  velocity = utils::numeric(FLERR,arg[4],false,lmp);
+  if (velocity < 0) error->all(FLERR,"Illegal fix qbmsst velocity value {}", velocity);
 
   // default parameters