--- a/src/variables.cc
+++ b/src/variables.cc
@@ -835,7 +835,10 @@
 
   // It is a prorgramming error to look for builtins that aren't.
 
-  assert (sr);
+  // Use != here to avoid possible conversion to int of smaller type
+  // than the sr pointer.
+
+  assert (sr != 0);
 
   std::string retval;
 
@@ -859,7 +862,10 @@
 
   // It is a prorgramming error to look for builtins that aren't.
 
-  assert (sr);
+  // Use != here to avoid possible conversion to int of smaller type
+  // than the sr pointer.
+
+  assert (sr != 0);
 
   octave_value val = sr->def ();
 
@@ -881,7 +887,10 @@
 
   // It is a prorgramming error to look for builtins that aren't.
 
-  assert (sr);
+  // Use != here to avoid possible conversion to int of smaller type
+  // than the sr pointer.
+
+  assert (sr != 0);
 
   return sr->def ();
 }
@@ -1256,7 +1265,10 @@
   // It is a programming error for a builtin symbol to be missing.
   // Besides, we just inserted it, so it must be there.
 
-  assert (sr);
+  // Use != here to avoid possible conversion to int of smaller type
+  // than the sr pointer.
+
+  assert (sr != 0);
 
   sr->unprotect ();