--- a/src/variables.cc	Thu Mar 25 18:19:19 2010 -0400
+++ b/src/variables.cc	Fri Mar 26 08:24:04 2010 +0100
@@ -2394,5 +2394,16 @@
 {
   // Don't do this if we're handling errors.
   if (buffer_error_messages == 0 && ! Vmissing_function_hook.empty ())
-    feval (Vmissing_function_hook, octave_value (name));
+    {
+      // Ensure auto-restoration.
+      unwind_protect frame;
+      frame.protect_var (Vmissing_function_hook);
+
+      // Clear the variable prior to calling the function.
+      const std::string func_name = Vmissing_function_hook;
+      Vmissing_function_hook.clear ();
+
+      // Call.
+      feval (func_name, octave_value (name));
+    }
 }