--- a/liboctave/chMatrix.cc
+++ b/liboctave/chMatrix.cc
@@ -38,8 +38,8 @@
 charMatrix::charMatrix (char c)
   : MArray2<char> ()
 {
-  int nc = 1;
-  int nr = 1;
+  octave_idx_type nc = 1;
+  octave_idx_type nr = 1;
 
   resize (nr, nc);
 
@@ -49,36 +49,36 @@
 charMatrix::charMatrix (const char *s)
   : MArray2<char> ()
 {
-  int nc = s ? strlen (s) : 0;
-  int nr = s && nc > 0 ? 1 : 0;
+  octave_idx_type nc = s ? strlen (s) : 0;
+  octave_idx_type nr = s && nc > 0 ? 1 : 0;
 
   resize (nr, nc);
 
-  for (int i = 0; i < nc; i++)
+  for (octave_idx_type i = 0; i < nc; i++)
     elem (0, i) = s[i];
 }
 
 charMatrix::charMatrix (const std::string& s)
   : MArray2<char> ()
 {
-  int nc = s.length ();
-  int nr = nc > 0 ? 1 : 0;
+  octave_idx_type nc = s.length ();
+  octave_idx_type nr = nc > 0 ? 1 : 0;
 
   resize (nr, nc);
 
-  for (int i = 0; i < nc; i++)
+  for (octave_idx_type i = 0; i < nc; i++)
     elem (0, i) = s[i];
 }
 
 charMatrix::charMatrix (const string_vector& s)
   : MArray2<char> (s.length (), s.max_length (), 0)
 {
-  int nr = rows ();
+  octave_idx_type nr = rows ();
 
-  for (int i = 0; i < nr; i++)
+  for (octave_idx_type i = 0; i < nr; i++)
     {
-      int nc = s[i].length ();
-      for (int j = 0; j < nc; j++)
+      octave_idx_type nc = s[i].length ();
+      for (octave_idx_type j = 0; j < nc; j++)
 	elem (i, j) = s[i][j];
     }
 }
@@ -99,11 +99,11 @@
 }
 
 charMatrix&
-charMatrix::insert (const char *s, int r, int c)
+charMatrix::insert (const char *s, octave_idx_type r, octave_idx_type c)
 {
   if (s)
     {
-      int s_len = strlen (s);
+      octave_idx_type s_len = strlen (s);
 
       if (r < 0 || r >= rows () || c < 0 || c + s_len - 1 > cols ())
 	{
@@ -111,26 +111,26 @@
 	  return *this;
 	}
 
-      for (int i = 0; i < s_len; i++)
+      for (octave_idx_type i = 0; i < s_len; i++)
 	elem (r, c+i) = s[i];
     }
   return *this;
 }
 
 charMatrix&
-charMatrix::insert (const charMatrix& a, int r, int c)
+charMatrix::insert (const charMatrix& a, octave_idx_type r, octave_idx_type c)
 {
   Array2<char>::insert (a, r, c);
   return *this;
 }
 
 std::string
-charMatrix::row_as_string (int r, bool strip_ws, bool raw) const 
+charMatrix::row_as_string (octave_idx_type r, bool strip_ws, bool raw) const 
 {
   std::string retval;
 
-  int nr = rows ();
-  int nc = cols ();
+  octave_idx_type nr = rows ();
+  octave_idx_type nc = cols ();
 
   if (r == 0 && nr == 0 && nc == 0)
     return retval;
@@ -143,7 +143,7 @@
 
   retval.resize (nc, '\0');
 
-  for (int i = 0; i < nc; i++)
+  for (octave_idx_type i = 0; i < nc; i++)
     retval[i] = elem (r, i);
 
   if (! raw)
@@ -171,18 +171,18 @@
 }
 
 charMatrix
-charMatrix::extract (int r1, int c1, int r2, int c2) const
+charMatrix::extract (octave_idx_type r1, octave_idx_type c1, octave_idx_type r2, octave_idx_type c2) const
 {
-  if (r1 > r2) { int tmp = r1; r1 = r2; r2 = tmp; }
-  if (c1 > c2) { int tmp = c1; c1 = c2; c2 = tmp; }
+  if (r1 > r2) { octave_idx_type tmp = r1; r1 = r2; r2 = tmp; }
+  if (c1 > c2) { octave_idx_type tmp = c1; c1 = c2; c2 = tmp; }
 
-  int new_r = r2 - r1 + 1;
-  int new_c = c2 - c1 + 1;
+  octave_idx_type new_r = r2 - r1 + 1;
+  octave_idx_type new_c = c2 - c1 + 1;
 
   charMatrix result (new_r, new_c);
 
-  for (int j = 0; j < new_c; j++)
-    for (int i = 0; i < new_r; i++)
+  for (octave_idx_type j = 0; j < new_c; j++)
+    for (octave_idx_type i = 0; i < new_r; i++)
       result.elem (i, j) = elem (r1+i, c1+j);
 
   return result;