Index: ext/fts5/fts5_expr.c
==================================================================
--- ext/fts5/fts5_expr.c
+++ ext/fts5/fts5_expr.c
@@ -58,11 +58,11 @@
   Fts5ExprNearset *pNear;         /* For FTS5_STRING - cluster of phrases */
 
   /* Child nodes. For a NOT node, this array always contains 2 entries. For 
   ** AND or OR nodes, it contains 2 or more entries.  */
   int nChild;                     /* Number of child nodes */
-  Fts5ExprNode *apChild[0];       /* Array of child nodes */
+  Fts5ExprNode *apChild[1];       /* Array of child nodes */
 };
 
 #define Fts5NodeIsString(p) ((p)->eType==FTS5_TERM || (p)->eType==FTS5_STRING)
 
 /*
@@ -1617,11 +1617,11 @@
       nChild = 2;
       if( pLeft->eType==eType ) nChild += pLeft->nChild-1;
       if( pRight->eType==eType ) nChild += pRight->nChild-1;
     }
 
-    nByte = sizeof(Fts5ExprNode) + sizeof(Fts5ExprNode*)*nChild;
+    nByte = sizeof(Fts5ExprNode) + sizeof(Fts5ExprNode*)*(nChild-1);
     pRet = (Fts5ExprNode*)sqlite3Fts5MallocZero(&pParse->rc, nByte);
 
     if( pRet ){
       pRet->eType = eType;
       pRet->pNear = pNear;

Index: ext/fts5/fts5_index.c
==================================================================
--- ext/fts5/fts5_index.c
+++ ext/fts5/fts5_index.c
@@ -3752,17 +3752,17 @@
   assert( iLvl>=0 );
   for(fts5MultiIterNew(p, pStruct, 0, 0, 0, 0, iLvl, nInput, &pIter);
       fts5MultiIterEof(p, pIter)==0;
       fts5MultiIterNext(p, pIter, 0, 0)
   ){
-    Fts5SegIter *pSeg = &pIter->aSeg[ pIter->aFirst[1].iFirst ];
+    Fts5SegIter *pSegIter = &pIter->aSeg[ pIter->aFirst[1].iFirst ];
     int nPos;                     /* position-list size field value */
     int nTerm;
     const u8 *pTerm;
 
     /* Check for key annihilation. */
-    if( pSeg->nPos==0 && (bOldest || pSeg->bDel==0) ) continue;
+    if( pSegIter->nPos==0 && (bOldest || pSegIter->bDel==0) ) continue;
 
     pTerm = fts5MultiIterTerm(pIter, &nTerm);
     if( nTerm!=term.n || memcmp(pTerm, term.p, nTerm) ){
       if( pnRem && writer.nLeafWritten>nRem ){
         break;
@@ -3777,15 +3777,15 @@
       bRequireDoclistTerm = 1;
     }
 
     /* Append the rowid to the output */
     /* WRITEPOSLISTSIZE */
-    nPos = pSeg->nPos*2 + pSeg->bDel;
+    nPos = pSegIter->nPos*2 + pSegIter->bDel;
     fts5WriteAppendRowid(p, &writer, fts5MultiIterRowid(pIter), nPos);
 
     /* Append the position-list data to the output */
-    fts5ChunkIterate(p, pSeg, (void*)&writer, fts5MergeChunkCallback);
+    fts5ChunkIterate(p, pSegIter, (void*)&writer, fts5MergeChunkCallback);
   }
 
   /* Flush the last leaf page to disk. Set the output segment b-tree height
   ** and last leaf page number at the same time.  */
   fts5WriteFinish(p, &writer, &pSeg->nHeight, &pSeg->pgnoLast);