Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -1341,11 +1341,14 @@
   ** Note that the virtual term must be tagged with TERM_VNULL.  This
   ** TERM_VNULL tag will suppress the not-null check at the beginning
   ** of the loop.  Without the TERM_VNULL flag, the not-null check at
   ** the start of the loop will prevent any results from being returned.
   */
-  if( pExpr->op==TK_NOTNULL && pExpr->pLeft->iColumn>=0 ){
+  if( pExpr->op==TK_NOTNULL
+   && pExpr->pLeft->op==TK_COLUMN
+   && pExpr->pLeft->iColumn>=0
+  ){
     Expr *pNewExpr;
     Expr *pLeft = pExpr->pLeft;
     int idxNew;
     WhereTerm *pNewTerm;