diff -r 910737d41605 libinterp/octave-value/ov.cc
--- a/libinterp/octave-value/ov.cc	Mon Oct 14 17:33:24 2019 -0700
+++ b/libinterp/octave-value/ov.cc	Tue Oct 15 11:14:04 2019 -0700
@@ -25,6 +25,9 @@ along with Octave; see the file COPYING.
 #  include "config.h"
 #endif
 
+#include <iostream>
+
+
 #include "data-conv.h"
 #include "quit.h"
 #include "str-vec.h"
@@ -2510,6 +2513,9 @@ do_colon_op (const octave_value& base, c
 {
   octave_value retval;
 
+  //warning ("running do_colon_op");
+  std::cerr << "running do_colon_op\n";
+
   if (base.isobject () || increment.isobject () || limit.isobject ())
     {
       std::string dispatch_type;
@@ -2550,6 +2556,14 @@ do_colon_op (const octave_value& base, c
       bool result_is_str = (base.is_string () && limit.is_string ());
       bool dq_str = (base.is_dq_string () || limit.is_dq_string ());
 
+      if (base.numel () > 1 || limit.numel () > 1
+          || (increment.is_defined () && increment.numel () > 1))
+        {
+          std::cerr << "Got here\n";
+          warning ("colon arguments should be scalars");
+          std::cerr << "Got here2\n";
+        }
+
       if (base.iscomplex () || limit.iscomplex ()
           || (increment.is_defined () && increment.iscomplex ()))
         warning ("imaginary part of complex colon arguments is ignored");