diff --git a/src/fix_ave_correlate.cpp b/src/fix_ave_correlate.cpp
index d506e17761..50ea6a5614 100644
--- a/src/fix_ave_correlate.cpp
+++ b/src/fix_ave_correlate.cpp
@@ -121,7 +121,7 @@ FixAveCorrelate::FixAveCorrelate(LAMMPS *lmp, int narg, char **arg) :
       prefactor = utils::numeric(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
     } else if (strcmp(arg[iarg],"file") == 0) {
-      if (iarg+2 > narg) utils::missing_cmd_args(FLERR, "fix ave/correlate file", error);
+      if (iarg+2 > nargnew) utils::missing_cmd_args(FLERR, "fix ave/correlate file", error);
       if (comm->me == 0) {
         fp = fopen(arg[iarg+1],"w");
         if (fp == nullptr)
diff --git a/src/fix_ave_time.cpp b/src/fix_ave_time.cpp
index 5219a4de3d..c88d8e1659 100644
--- a/src/fix_ave_time.cpp
+++ b/src/fix_ave_time.cpp
@@ -178,7 +178,7 @@ FixAveTime::FixAveTime(LAMMPS *lmp, int narg, char **arg) :
       if (val.argindex && (val.val.f->array_flag == 0))
         error->all(FLERR,"Fix ave/time fix {} does not calculate an array", val.id);
       if (val.argindex && (val.val.f->size_array_rows_variable))
-        error->all(FLERR,"Fix ave/time fix {} array cannot be variable length", val.id);
+        error->all(FLERR,"Fix ave/time fix {} array cannot have variable row length", val.id);
       if (val.argindex && (val.argindex > val.val.f->size_array_cols))
         error->all(FLERR,"Fix ave/time fix {} array is accessed out-of-range", val.id);
       if (nevery % val.val.f->global_freq)
diff --git a/src/thermo.cpp b/src/thermo.cpp
index efc5f984fc..dbb8b2530e 100644
--- a/src/thermo.cpp
+++ b/src/thermo.cpp
@@ -1490,9 +1490,8 @@ void Thermo::compute_compute()
     if (normflag && compute->extscalar) dvalue /= natoms;
   } else if (compute_which[m] == VECTOR) {
     if (compute->size_vector_variable && argindex1[ifield] > compute->size_vector)
-      dvalue = 0.0;
-    else
-      dvalue = compute->vector[argindex1[ifield] - 1];
+      error->all(FLERR, "Thermo compute vector is accessed out-of-range");
+    dvalue = compute->vector[argindex1[ifield] - 1];
     if (normflag) {
       if (compute->extvector == 0)
         return;
@@ -1503,9 +1502,8 @@ void Thermo::compute_compute()
     }
   } else {
     if (compute->size_array_rows_variable && argindex1[ifield] > compute->size_array_rows)
-      dvalue = 0.0;
-    else
-      dvalue = compute->array[argindex1[ifield] - 1][argindex2[ifield] - 1];
+      error->all(FLERR, "Thermo compute array is accessed out-of-range");
+    dvalue = compute->array[argindex1[ifield] - 1][argindex2[ifield] - 1];
     if (normflag && compute->extarray) dvalue /= natoms;
   }
 }
@@ -1521,6 +1519,8 @@ void Thermo::compute_fix()
     dvalue = fix->compute_scalar();
     if (normflag && fix->extscalar) dvalue /= natoms;
   } else if (argindex2[ifield] == 0) {
+    if (fix->size_vector_variable && argindex1[ifield] > fix->size_vector)
+      error->all(FLERR, "Thermo fix vector is accessed out-of-range");
     dvalue = fix->compute_vector(argindex1[ifield] - 1);
     if (normflag) {
       if (fix->extvector == 0)
@@ -1531,6 +1531,8 @@ void Thermo::compute_fix()
         dvalue /= natoms;
     }
   } else {
+    if (fix->size_array_rows_variable && argindex1[ifield] > fix->size_array_rows)
+      error->all(FLERR, "Thermo fix array is accessed out-of-range");
     dvalue = fix->compute_array(argindex1[ifield] - 1, argindex2[ifield] - 1);
     if (normflag && fix->extarray) dvalue /= natoms;
   }
@@ -1547,10 +1549,8 @@ void Thermo::compute_variable()
   else {
     double *varvec;
     int nvec = input->variable->compute_vector(variables[field2index[ifield]], &varvec);
-    if (nvec < iarg)
-      dvalue = 0.0;
-    else
-      dvalue = varvec[iarg - 1];
+    if (iarg > nvec) error->all(FLERR, "Thermo vector-style variable is accessed out-of-range");
+    dvalue = varvec[iarg - 1];
   }
 }
 
diff --git a/src/variable.cpp b/src/variable.cpp
index 8124d9c4a1..a6a194779c 100644
--- a/src/variable.cpp
+++ b/src/variable.cpp
@@ -1225,7 +1225,6 @@ int Variable::compute_vector(int ivar, double **result)
   int nlen = size_tree_vector(tree);
   if (nlen == 0)
     print_var_error(FLERR,"Vector-style variable has zero length",ivar);
-
   if (nlen < 0)
     print_var_error(FLERR,"Inconsistent lengths in vector-style variable",ivar);
 
@@ -1535,9 +1534,6 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
 
             if (!compute->vector_flag)
               print_var_error(FLERR,"Mismatched compute in variable formula",ivar);
-            if (index1 > compute->size_vector &&
-                compute->size_vector_variable == 0)
-              print_var_error(FLERR,"Variable formula compute vector is accessed out-of-range",ivar,0);
             if (!compute->is_initialized())
               print_var_error(FLERR,"Variable formula compute cannot be invoked before "
                               "initialization by a run",ivar);
@@ -1546,10 +1542,14 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
               compute->invoked_flag |= Compute::INVOKED_VECTOR;
             }
 
-          if (compute->size_vector_variable &&
-              index1 > compute->size_vector) value1 = 0.0;
-          else value1 = compute->vector[index1-1];
-          argstack[nargstack++] = value1;
+            // wait to check index1 until after compute invocation
+            // to allow for computes with size_vector_variable == 1
+            
+            if (index1 > compute->size_vector)
+              print_var_error(FLERR,"Variable formula compute vector is accessed out-of-range",ivar,0);
+
+            value1 = compute->vector[index1-1];
+            argstack[nargstack++] = value1;
 
           // c_ID[i][j] = scalar from global array
 
@@ -1557,9 +1557,6 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
 
             if (!compute->array_flag)
               print_var_error(FLERR,"Mismatched compute in variable formula",ivar);
-            if (index1 > compute->size_array_rows &&
-                compute->size_array_rows_variable == 0)
-              print_var_error(FLERR,"Variable formula compute array is accessed out-of-range",ivar,0);
             if (index2 > compute->size_array_cols)
               print_var_error(FLERR,"Variable formula compute array is accessed out-of-range",ivar,0);
             if (!compute->is_initialized())
@@ -1570,9 +1567,13 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
               compute->invoked_flag |= Compute::INVOKED_ARRAY;
             }
 
-            if (compute->size_array_rows_variable &&
-                index1 > compute->size_array_rows) value1 = 0.0;
-            else value1 = compute->array[index1-1][index2-1];
+            // wait to check index1 until after compute invocation
+            // to allow for computes with size_array_rows_variable == 1
+
+            if (index1 > compute->size_array_rows)
+              print_var_error(FLERR,"Variable formula compute array is accessed out-of-range",ivar,0);
+              
+            value1 = compute->array[index1-1][index2-1];
             argstack[nargstack++] = value1;
 
           // C_ID[i] = scalar element of per-atom vector, note uppercase "C"
@@ -1634,8 +1635,6 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
 
             if (!compute->vector_flag)
               print_var_error(FLERR,"Mismatched compute in variable formula",ivar);
-            if (compute->size_vector == 0)
-              print_var_error(FLERR,"Variable formula compute vector is zero length",ivar);
             if (!compute->is_initialized())
               print_var_error(FLERR,"Variable formula compute cannot be invoked before "
                               "initialization by a run",ivar);
@@ -1644,6 +1643,12 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
               compute->invoked_flag |= Compute::INVOKED_VECTOR;
             }
 
+            // wait to check vector size until after compute invocation
+            // to allow for computes with size_vector_variable == 1
+            
+            if (compute->size_vector == 0)
+              print_var_error(FLERR,"Variable formula compute vector is zero length",ivar);
+
             auto newtree = new Tree();
             newtree->type = VECTORARRAY;
             newtree->array = compute->vector;
@@ -1657,8 +1662,6 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
 
             if (!compute->array_flag)
               print_var_error(FLERR,"Mismatched compute in variable formula",ivar);
-            if (compute->size_array_rows == 0)
-              print_var_error(FLERR,"Variable formula compute array is zero length",ivar);
             if (index1 > compute->size_array_cols)
               print_var_error(FLERR,"Variable formula compute array is accessed out-of-range",ivar,0);
             if (!compute->is_initialized())
@@ -1669,6 +1672,12 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
               compute->invoked_flag |= Compute::INVOKED_ARRAY;
             }
 
+            // wait to check row count until after compute invocation
+            // to allow for computes with size_array_rows_variable == 1
+            
+            if (compute->size_array_rows == 0)
+              print_var_error(FLERR,"Variable formula compute array has zero rows",ivar);
+
             auto newtree = new Tree();
             newtree->type = VECTORARRAY;
             newtree->array = &compute->array[0][index1-1];
@@ -1798,8 +1807,7 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
 
             if (!fix->vector_flag)
               print_var_error(FLERR,"Mismatched fix in variable formula",ivar);
-            if (index1 > fix->size_vector &&
-                fix->size_vector_variable == 0)
+            if (index1 > fix->size_vector)
               print_var_error(FLERR,"Variable formula fix vector is accessed out-of-range",ivar,0);
             if (update->whichflag > 0 && update->ntimestep % fix->global_freq)
               print_var_error(FLERR,"Fix in variable not computed at a compatible time",ivar);
@@ -1813,8 +1821,7 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
 
             if (!fix->array_flag)
               print_var_error(FLERR,"Mismatched fix in variable formula",ivar);
-            if (index1 > fix->size_array_rows &&
-                fix->size_array_rows_variable == 0)
+            if (index1 > fix->size_array_rows)
               print_var_error(FLERR,"Variable formula fix array is accessed out-of-range",ivar,0);
             if (index2 > fix->size_array_cols)
               print_var_error(FLERR,"Variable formula fix array is accessed out-of-range",ivar,0);