Index: base/applications/calc/calc.h
===================================================================
--- base/applications/calc/calc.h	(revision 71056)
+++ base/applications/calc/calc.h	(working copy)
@@ -1,6 +1,7 @@
 #ifndef _CALC_H
 #define _CALC_H
 
+#include <assert.h>
 #include <stdarg.h>
 #include <windef.h>
 #include <winuser.h>
Index: base/applications/calc/convert.c
===================================================================
--- base/applications/calc/convert.c	(revision 71056)
+++ base/applications/calc/convert.c	(working copy)
@@ -552,6 +552,9 @@
         }
     }
 
+    /* We should have found items at this point*/
+    assert(items);
+
     /* The units can be sorted, so I must search the exact match */
     item = items;
     SendDlgItemMessage(hWnd, IDC_COMBO_FROM, CB_GETLBTEXT, from, (LPARAM)txt_cb);