Index: src/vdbeaux.c
==================================================================
--- src/vdbeaux.c
+++ src/vdbeaux.c
@@ -4555,11 +4555,13 @@
 
   /* The index entry must begin with a header size */
   (void)getVarint32((u8*)m.z, szHdr);
   testcase( szHdr==3 );
   testcase( szHdr==m.n );
-  if( unlikely(szHdr<3 || (int)szHdr>m.n) ){
+  testcase( szHdr>0x7fffffff );
+  assert( m.n>=0 );
+  if( unlikely(szHdr<3 || szHdr>(unsigned)m.n) ){
     goto idx_rowid_corruption;
   }
 
   /* The last field of the index should be an integer - the ROWID.
   ** Verify that the last entry really is an integer. */