diff --git a/src/variable.cpp b/src/variable.cpp
index 2bde0e5adb..c1cf978028 100644
--- a/src/variable.cpp
+++ b/src/variable.cpp
@@ -1660,14 +1660,16 @@ double Variable::evaluate(char *str, Tree **tree, int ivar)
             if (!compute->is_initialized())
               print_var_error(FLERR,"Variable formula compute cannot be invoked before "
                               "initialization by a run",ivar);
+            if (index1 > compute->size_array_cols)
+              print_var_error(FLERR,"Variable formula compute array is accessed out-of-range",ivar,0);
             if (!(compute->invoked_flag & Compute::INVOKED_ARRAY)) {
               compute->compute_array();
               compute->invoked_flag |= Compute::INVOKED_ARRAY;
             }
+            // wait until after compute invocation to check size_array_rows
+            // b/c may be zero until after initial invocation
             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);
 
             auto newtree = new Tree();
             newtree->type = VECTORARRAY;