diff --git a/src/dump_custom.cpp b/src/dump_custom.cpp
index 0e47671bb9..5d371d3145 100644
--- a/src/dump_custom.cpp
+++ b/src/dump_custom.cpp
@@ -322,23 +322,21 @@ void DumpCustom::init_style()
   // check that fix frequency is acceptable
 
   for (i = 0; i < ncompute; i++) {
-    int icompute = modify->find_compute(id_compute[i]);
-    if (icompute < 0) error->all(FLERR,"Could not find dump custom compute ID");
-    compute[i] = modify->compute[icompute];
+    compute[i] = modify->get_compute_by_id(id_compute[i]);
+    if (!compute[i]) error->all(FLERR,"Could not find dump custom compute ID {}",id_compute[i]);
   }
 
   for (i = 0; i < nfix; i++) {
-    int ifix = modify->find_fix(id_fix[i]);
-    if (ifix < 0) error->all(FLERR,"Could not find dump custom fix ID");
-    fix[i] = modify->fix[ifix];
-    if (nevery % modify->fix[ifix]->peratom_freq)
+    fix[i] = modify->get_fix_by_id(id_fix[i]);
+    if (!fix[i]) error->all(FLERR,"Could not find dump custom fix ID {}", id_fix[i]);
+    if (nevery % fix[i]->peratom_freq)
       error->all(FLERR,"Dump custom and fix not computed at compatible times");
   }
 
   for (i = 0; i < nvariable; i++) {
     int ivariable = input->variable->find(id_variable[i]);
     if (ivariable < 0)
-      error->all(FLERR,"Could not find dump custom variable name");
+      error->all(FLERR,"Could not find dump custom variable name {}", id_variable[i]);
     variable[i] = ivariable;
   }
 
@@ -1446,10 +1444,12 @@ int DumpCustom::parse_fields(int narg, char **arg)
 
     } else {
       int n,flag,cols;
-      ArgInfo argi(arg[iarg],ArgInfo::COMPUTE|ArgInfo::FIX|ArgInfo::VARIABLE
-                   |ArgInfo::DNAME|ArgInfo::INAME);
+      ArgInfo argi(arg[iarg], ArgInfo::COMPUTE | ArgInfo::FIX | ArgInfo::VARIABLE |
+                   ArgInfo::DNAME | ArgInfo::INAME);
       argindex[iarg] = argi.get_index1();
       auto name = argi.get_name();
+      Compute *icompute = nullptr;
+      Fix *ifix = nullptr;
 
       switch (argi.get_type()) {
 
@@ -1464,16 +1464,15 @@ int DumpCustom::parse_fields(int narg, char **arg)
         pack_choice[iarg] = &DumpCustom::pack_compute;
         vtype[iarg] = Dump::DOUBLE;
 
-        n = modify->find_compute(name);
-        if (n < 0) error->all(FLERR,"Could not find dump custom compute ID: {}",name);
-        if (modify->compute[n]->peratom_flag == 0)
+        icompute = modify->get_compute_by_id(name);
+        if (!icompute) error->all(FLERR,"Could not find dump custom compute ID: {}",name);
+        if (icompute->peratom_flag == 0)
           error->all(FLERR,"Dump custom compute {} does not compute per-atom info",name);
-        if (argi.get_dim() == 0 && modify->compute[n]->size_peratom_cols > 0)
+        if (argi.get_dim() == 0 && icompute->size_peratom_cols > 0)
           error->all(FLERR,"Dump custom compute {} does not calculate per-atom vector",name);
-        if (argi.get_dim() > 0 && modify->compute[n]->size_peratom_cols == 0)
+        if (argi.get_dim() > 0 && icompute->size_peratom_cols == 0)
           error->all(FLERR,"Dump custom compute {} does not calculate per-atom array",name);
-        if (argi.get_dim() > 0 &&
-            argi.get_index1() > modify->compute[n]->size_peratom_cols)
+        if (argi.get_dim() > 0 && argi.get_index1() > icompute->size_peratom_cols)
           error->all(FLERR,"Dump custom compute {} vector is accessed out-of-range",name);
 
         field2index[iarg] = add_compute(name);
@@ -1486,16 +1485,15 @@ int DumpCustom::parse_fields(int narg, char **arg)
         pack_choice[iarg] = &DumpCustom::pack_fix;
         vtype[iarg] = Dump::DOUBLE;
 
-        n = modify->find_fix(name);
-        if (n < 0) error->all(FLERR,"Could not find dump custom fix ID: {}",name);
-        if (modify->fix[n]->peratom_flag == 0)
+        ifix = modify->get_fix_by_id(name);
+        if (!ifix) error->all(FLERR,"Could not find dump custom fix ID: {}",name);
+        if (ifix->peratom_flag == 0)
           error->all(FLERR,"Dump custom fix {} does not compute per-atom info",name);
-        if (argi.get_dim() == 0 && modify->fix[n]->size_peratom_cols > 0)
+        if (argi.get_dim() == 0 && ifix->size_peratom_cols > 0)
           error->all(FLERR,"Dump custom fix {} does not compute per-atom vector",name);
-        if (argi.get_dim() > 0 && modify->fix[n]->size_peratom_cols == 0)
+        if (argi.get_dim() > 0 && ifix->size_peratom_cols == 0)
           error->all(FLERR,"Dump custom fix {} does not compute per-atom array",name);
-        if (argi.get_dim() > 0 &&
-            argi.get_index1() > modify->fix[n]->size_peratom_cols)
+        if (argi.get_dim() > 0 && argi.get_index1() > ifix->size_peratom_cols)
           error->all(FLERR,"Dump custom fix {} vector is accessed out-of-range",name);
 
         field2index[iarg] = add_fix(name);
@@ -1878,10 +1876,12 @@ int DumpCustom::modify_param(int narg, char **arg)
       memory->grow(argindex,nfield+nthresh+1,"dump:argindex");
 
       int n,flag,cols;
-      ArgInfo argi(arg[1],ArgInfo::COMPUTE|ArgInfo::FIX|ArgInfo::VARIABLE
-                   |ArgInfo::DNAME|ArgInfo::INAME);
+      ArgInfo argi(arg[1], ArgInfo::COMPUTE | ArgInfo::FIX | ArgInfo::VARIABLE |
+                   ArgInfo::DNAME | ArgInfo::INAME);
       argindex[nfield+nthresh] = argi.get_index1();
       auto name = argi.get_name();
+      Compute *icompute = nullptr;
+      Fix *ifix = nullptr;
 
       switch (argi.get_type()) {
 
@@ -1894,17 +1894,16 @@ int DumpCustom::modify_param(int narg, char **arg)
 
       case ArgInfo::COMPUTE:
         thresh_array[nthresh] = COMPUTE;
-        n = modify->find_compute(name);
-        if (n < 0) error->all(FLERR,"Could not find dump modify compute ID: {}",name);
 
-        if (modify->compute[n]->peratom_flag == 0)
+        icompute = modify->get_compute_by_id(name);
+        if (!icompute) error->all(FLERR,"Could not find dump modify compute ID {}",name);
+        if (icompute->peratom_flag == 0)
           error->all(FLERR,"Dump modify compute ID {} does not compute per-atom info",name);
-        if (argi.get_dim() == 0 && modify->compute[n]->size_peratom_cols > 0)
+        if (argi.get_dim() == 0 && icompute->size_peratom_cols > 0)
           error->all(FLERR,"Dump modify compute ID {} does not compute per-atom vector",name);
-        if (argi.get_index1() > 0 && modify->compute[n]->size_peratom_cols == 0)
+        if (argi.get_index1() > 0 && icompute->size_peratom_cols == 0)
           error->all(FLERR,"Dump modify compute ID {} does not compute per-atom array",name);
-        if (argi.get_index1() > 0 &&
-            argi.get_index1() > modify->compute[n]->size_peratom_cols)
+        if (argi.get_index1() > 0 && argi.get_index1() > icompute->size_peratom_cols)
           error->all(FLERR,"Dump modify compute ID {} vector is not large enough",name);
 
         field2index[nfield+nthresh] = add_compute(name);
@@ -1915,16 +1914,17 @@ int DumpCustom::modify_param(int narg, char **arg)
 
       case ArgInfo::FIX:
         thresh_array[nthresh] = FIX;
-        n = modify->find_fix(name);
-        if (n < 0) error->all(FLERR,"Could not find dump modify fix ID: {}",name);
 
-        if (modify->fix[n]->peratom_flag == 0)
+        ifix = modify->get_fix_by_id(name);
+        if (!ifix) error->all(FLERR,"Could not find dump modify fix ID: {}",name);
+
+        if (ifix->peratom_flag == 0)
           error->all(FLERR,"Dump modify fix ID {} does not compute per-atom info",name);
-        if (argi.get_dim() == 0 && modify->fix[n]->size_peratom_cols > 0)
+        if (argi.get_dim() == 0 && ifix->size_peratom_cols > 0)
           error->all(FLERR,"Dump modify fix ID {} does not compute per-atom vector",name);
-        if (argi.get_index1() > 0 && modify->fix[n]->size_peratom_cols == 0)
+        if (argi.get_index1() > 0 && ifix->size_peratom_cols == 0)
           error->all(FLERR,"Dump modify fix ID {} does not compute per-atom array",name);
-        if (argi.get_index1() > 0 && argi.get_index1() > modify->fix[n]->size_peratom_cols)
+        if (argi.get_index1() > 0 && argi.get_index1() > ifix->size_peratom_cols)
           error->all(FLERR,"Dump modify fix ID {} vector is not large enough",name);
 
         field2index[nfield+nthresh] = add_fix(name);
diff --git a/src/dump_image.cpp b/src/dump_image.cpp
index 69ad3b7769..0179878111 100644
--- a/src/dump_image.cpp
+++ b/src/dump_image.cpp
@@ -351,9 +351,9 @@ DumpImage::DumpImage(LAMMPS *lmp, int narg, char **arg) :
   if (lineflag || triflag || bodyflag) extraflag = 1;
 
   if (fixflag) {
-    int ifix = modify->find_fix(fixID);
-    if (ifix < 0) error->all(FLERR,"Fix ID for dump image does not exist");
-    fixptr = modify->fix[ifix];
+    fixptr = modify->get_fix_by_id(fixID);
+    if (!fixptr) error->all(FLERR,"Fix ID {} for dump image does not exist", fixID);
+
   }
 
   // allocate image buffer now that image size is known
diff --git a/src/dump_local.cpp b/src/dump_local.cpp
index 96d8944e2f..8ed1f62fe2 100644
--- a/src/dump_local.cpp
+++ b/src/dump_local.cpp
@@ -197,17 +197,15 @@ void DumpLocal::init_style()
   // check that fix frequency is acceptable
 
   for (i = 0; i < ncompute; i++) {
-    int icompute = modify->find_compute(id_compute[i]);
-    if (icompute < 0) error->all(FLERR,"Could not find dump local compute ID");
-    compute[i] = modify->compute[icompute];
+    compute[i] = modify->get_compute_by_id(id_compute[i]);
+    if (!compute[i]) error->all(FLERR,"Could not find dump local compute ID {}",id_compute[i]);
   }
 
   for (i = 0; i < nfix; i++) {
-    int ifix = modify->find_fix(id_fix[i]);
-    if (ifix < 0) error->all(FLERR,"Could not find dump local fix ID");
-    fix[i] = modify->fix[ifix];
-    if (nevery % modify->fix[ifix]->local_freq)
-      error->all(FLERR,"Dump local and fix not computed at compatible times");
+    fix[i] = modify->get_fix_by_id(id_fix[i]);
+    if (!fix[i]) error->all(FLERR,"Could not find dump local fix ID {}", id_fix[i]);
+    if (nevery % fix[i]->local_freq)
+      error->all(FLERR,"Dump local and fix {} not computed at compatible times", id_fix[i]);
   }
 
   // open single file, one time only
@@ -442,6 +440,9 @@ void DumpLocal::parse_fields(int narg, char **arg)
       computefixflag = 1;
       vtype[iarg] = Dump::DOUBLE;
       argindex[iarg] = argi.get_index1();
+      auto name = argi.get_name();
+      Compute *icompute = nullptr;
+      Fix *ifix = nullptr;
 
       switch (argi.get_type()) {
 
@@ -451,19 +452,18 @@ void DumpLocal::parse_fields(int narg, char **arg)
       case ArgInfo::COMPUTE:
         pack_choice[iarg] = &DumpLocal::pack_compute;
 
-        n = modify->find_compute(argi.get_name());
-        if (n < 0) error->all(FLERR,"Could not find dump local compute ID");
-        if (modify->compute[n]->local_flag == 0)
-          error->all(FLERR,"Dump local compute does not compute local info");
-        if (argi.get_dim() == 0 && modify->compute[n]->size_local_cols > 0)
-          error->all(FLERR,"Dump local compute does not calculate local vector");
-        if (argi.get_index1() > 0 && modify->compute[n]->size_local_cols == 0)
-          error->all(FLERR,"Dump local compute does not calculate local array");
-        if (argi.get_index1() > 0 &&
-            argi.get_index1() > modify->compute[n]->size_local_cols)
-          error->all(FLERR,"Dump local compute vector is accessed out-of-range");
+        icompute = modify->get_compute_by_id(name);
+        if (!icompute) error->all(FLERR,"Could not find dump local compute ID {}",name);
+        if (icompute->local_flag == 0)
+          error->all(FLERR,"Dump local compute {} does not compute local info", name);
+        if (argi.get_dim() == 0 && icompute->size_local_cols > 0)
+          error->all(FLERR,"Dump local compute {} does not calculate local vector", name);
+        if (argi.get_index1() > 0 && icompute->size_local_cols == 0)
+          error->all(FLERR,"Dump local compute {} does not calculate local array", name);
+        if (argi.get_index1() > 0 && argi.get_index1() > icompute->size_local_cols)
+          error->all(FLERR,"Dump local compute {} vector is accessed out-of-range", name);
 
-        field2index[iarg] = add_compute(argi.get_name());
+        field2index[iarg] = add_compute(name);
         break;
 
         // fix value = f_ID
@@ -472,26 +472,25 @@ void DumpLocal::parse_fields(int narg, char **arg)
       case ArgInfo::FIX:
         pack_choice[iarg] = &DumpLocal::pack_fix;
 
-        n = modify->find_fix(argi.get_name());
-        if (n < 0) error->all(FLERR,"Could not find dump local fix ID");
-        if (modify->fix[n]->local_flag == 0)
-          error->all(FLERR,"Dump local fix does not compute local info");
-        if (argi.get_dim() == 0 && modify->fix[n]->size_local_cols > 0)
-          error->all(FLERR,"Dump local fix does not compute local vector");
-        if (argi.get_index1() > 0 && modify->fix[n]->size_local_cols == 0)
-          error->all(FLERR,"Dump local fix does not compute local array");
-        if (argi.get_index1() > 0 &&
-            argi.get_index1() > modify->fix[n]->size_local_cols)
-          error->all(FLERR,"Dump local fix vector is accessed out-of-range");
+        ifix = modify->get_fix_by_id(name);
+        if (!ifix) error->all(FLERR,"Could not find dump local fix ID {}", name);
+        if (ifix->local_flag == 0)
+          error->all(FLERR,"Dump local fix {} does not compute local info", name);
+        if (argi.get_dim() == 0 && ifix->size_local_cols > 0)
+          error->all(FLERR,"Dump local fix {} does not compute local vector", name);
+        if (argi.get_index1() > 0 && ifix->size_local_cols == 0)
+          error->all(FLERR,"Dump local fix {} does not compute local array", name);
+        if (argi.get_index1() > 0 && argi.get_index1() > ifix->size_local_cols)
+          error->all(FLERR,"Dump local fix {} vector is accessed out-of-range", name);
 
-        field2index[iarg] = add_fix(argi.get_name());
+        field2index[iarg] = add_fix(name);
         break;
 
       case ArgInfo::NONE:       // fallthrough
       case ArgInfo::UNKNOWN:    // fallthrough
       default:
-         error->all(FLERR,"Invalid attribute in dump local command");
-         break;
+        error->all(FLERR,"Invalid attribute {} in dump local command",arg[iarg]);
+        break;
       }
     }
   }