--- a/scripts/polynomial/pchip.m
+++ b/scripts/polynomial/pchip.m
@@ -125,7 +125,6 @@
 
 endfunction
 
-
 %!demo
 %! x = 0:8;
 %! y = [1, 1, 1, 1, 0.5, 0, 0, 0, 0];
@@ -169,3 +168,5 @@
 %!assert (size (yi2), [3,2,5,4])
 %!assert (squeeze (yi2(1,2,3,:)), [1/sqrt(2); 0; -1/sqrt(2);-1], 1e-14)
 
+%!error (pchip (1,2));
+%!error (pchip (1,2,3));

--- a/src/DLD-FUNCTIONS/__pchip_deriv__.cc
+++ b/src/DLD-FUNCTIONS/__pchip_deriv__.cc
@@ -69,6 +69,13 @@
           FloatMatrix ymat (args(1).float_matrix_value ());
 
           octave_idx_type nx = xvec.length ();
+
+          if (nx < 2)
+            {
+              error ("__pchip_deriv__: X must be at least of length 2");
+              return retval;
+            }
+
           octave_idx_type nyr = ymat.rows ();
           octave_idx_type nyc = ymat.columns ();
 
@@ -109,6 +116,13 @@
           Matrix ymat (args(1).matrix_value ());
 
           octave_idx_type nx = xvec.length ();
+
+          if (nx < 2)
+            {
+              error ("__pchip_deriv__: X must be at least of length 2");
+              return retval;
+            }
+
           octave_idx_type nyr = ymat.rows ();
           octave_idx_type nyc = ymat.columns ();
 

--- a/src/ov-base-scalar.h
+++ b/src/ov-base-scalar.h
@@ -71,6 +71,9 @@
                          const std::list<octave_value_list>& idx,
                          const octave_value& rhs);
 
+  octave_value_list do_multi_index_op (int, const octave_value_list& idx)
+    { return do_index_op (idx); }
+
   bool is_constant (void) const { return true; }
 
   bool is_defined (void) const { return true; }