Index: src/alter.c
==================================================================
--- src/alter.c
+++ src/alter.c
@@ -1414,11 +1414,12 @@
 */
 static int renameTableSelectCb(Walker *pWalker, Select *pSelect){
   int i;
   RenameCtx *p = pWalker->u.pRename;
   SrcList *pSrc = pSelect->pSrc;
-  if( NEVER(pSrc==0) ){
+  if( pSrc==0 ){
+    assert( pWalker->pParse->db->mallocFailed );
     return WRC_Abort;
   }
   for(i=0; i<pSrc->nSrc; i++){
     struct SrcList_item *pItem = &pSrc->a[i];
     if( pItem->pTab==p->pTab ){

Index: src/build.c
==================================================================
--- src/build.c
+++ src/build.c
@@ -4141,11 +4141,12 @@
 ** Assign VdbeCursor index numbers to all tables in a SrcList
 */
 void sqlite3SrcListAssignCursors(Parse *pParse, SrcList *pList){
   int i;
   struct SrcList_item *pItem;
-  if( ALWAYS(pList) ){
+  assert(pList || pParse->db->mallocFailed );
+  if( pList ){
     for(i=0, pItem=pList->a; i<pList->nSrc; i++, pItem++){
       if( pItem->iCursor>=0 ) break;
       pItem->iCursor = pParse->nTab++;
       if( pItem->pSelect ){
         sqlite3SrcListAssignCursors(pParse, pItem->pSelect->pSrc);

Index: src/expr.c
==================================================================
--- src/expr.c
+++ src/expr.c
@@ -184,11 +184,14 @@
         /* The Expr.x union is never used at the same time as Expr.pRight */
         assert( p->x.pList==0 || p->pRight==0 );
         /* p->flags holds EP_Collate and p->pLeft->flags does not.  And
         ** p->x.pSelect cannot.  So if p->x.pLeft exists, it must hold at
         ** least one EP_Collate. Thus the following two ALWAYS. */
-        if( p->x.pList!=0 && ALWAYS(!ExprHasProperty(p, EP_xIsSelect)) ){
+        if( p->x.pList!=0 
+         && !db->mallocFailed
+         && ALWAYS(!ExprHasProperty(p, EP_xIsSelect))
+        ){
           int i;
           for(i=0; ALWAYS(i<p->x.pList->nExpr); i++){
             if( ExprHasProperty(p->x.pList->a[i].pExpr, EP_Collate) ){
               pNext = p->x.pList->a[i].pExpr;
               break;
@@ -1528,14 +1531,10 @@
     *pp = pNew;
     pp = &pNew->pPrior;
     pNext = pNew;
   }
 
-  if( db->mallocFailed ){
-    sqlite3SelectDelete(db, pRet);
-    pRet = 0;
-  }
   return pRet;
 }
 #else
 Select *sqlite3SelectDup(sqlite3 *db, Select *p, int flags){
   assert( p==0 );

Index: test/collate1.test
==================================================================
--- test/collate1.test
+++ test/collate1.test
@@ -414,7 +414,26 @@
   CREATE TABLE t0(c0 COLLATE RTRIM, c1 BLOB UNIQUE,
                   PRIMARY KEY (c0, c1)) WITHOUT ROWID;
   INSERT INTO t0 VALUES (123, 3), (' ', 1), ('	', 2), ('', 4);
   SELECT * FROM t0 WHERE c1 = 1;
 } {{ } 1}
+
+# 2019-10-09
+# ALWAYS() macro fails following OOM
+# Problem detected by dbsqlfuzz.
+#
+do_execsql_test 9.0 {
+  CREATE TABLE t1(a, b);
+  CREATE TABLE t2(c, d);
+}
+
+do_faultsim_test 9.1 -faults oom* -body {
+  execsql {
+    SELECT * FROM (
+        SELECT b COLLATE nocase IN (SELECT c FROM t2) FROM t1
+    );
+  }
+} -test {
+  faultsim_test_result {0 {}}
+}
 
 finish_test