Index: ext/fts3/fts3_write.c
==================================================================
--- ext/fts3/fts3_write.c
+++ ext/fts3/fts3_write.c
@@ -1406,11 +1406,11 @@
 
   /* Check that the doclist does not appear to extend past the end of the
   ** b-tree node. And that the final byte of the doclist is 0x00. If either 
   ** of these statements is untrue, then the data structure is corrupt.
   */
-  if( pReader->nDoclist-(pReader->aDoclist-pReader->aNode) > pReader->nNode
+  if( pReader->nDoclist > pReader->nNode-(pReader->aDoclist-pReader->aNode)
    || (pReader->nPopulate==0 && pReader->aDoclist[pReader->nDoclist-1])
   ){
     return FTS_CORRUPT_VTAB;
   }
   return SQLITE_OK;