Index: src/select.c
==================================================================
--- src/select.c
+++ src/select.c
@@ -3793,16 +3793,22 @@
   Expr *pWhere,         /* The WHERE clause of the outer query */
   int iCursor           /* Cursor number of the subquery */
 ){
   Expr *pNew;
   int nChng = 0;
+  Select *pX;           /* For looping over compound SELECTs in pSubq */
   if( pWhere==0 ) return 0;
-  if( (pSubq->selFlags & (SF_Aggregate|SF_Recursive))!=0 ){
-     return 0; /* restrictions (1) and (2) */
+  for(pX=pSubq; pX; pX=pX->pPrior){
+    if( (pX->selFlags & (SF_Aggregate|SF_Recursive))!=0 ){
+      testcase( pX->selFlags & SF_Aggregate );
+      testcase( pX->selFlags & SF_Recursive );
+      testcase( pX!=pSubq );
+      return 0; /* restrictions (1) and (2) */
+    }
   }
   if( pSubq->pLimit!=0 ){
-     return 0; /* restriction (3) */
+    return 0; /* restriction (3) */
   }
   while( pWhere->op==TK_AND ){
     nChng += pushDownWhereTerms(db, pSubq, pWhere->pRight, iCursor);
     pWhere = pWhere->pLeft;
   }

Index: test/select4.test
==================================================================
--- test/select4.test
+++ test/select4.test
@@ -861,7 +861,44 @@
   SELECT * FROM t14 EXCEPT VALUES('a','b','c') EXCEPT VALUES(4,5,6)
 } {1 2 3}
 do_execsql_test select4-14.9 {
   SELECT * FROM t14 UNION ALL VALUES(3,2,1),(2,3,1),(1,2,3),(2,1,3);
 } {1 2 3 4 5 6 3 2 1 2 3 1 1 2 3 2 1 3}
+
+# Ticket https://www.sqlite.org/src/tktview/f7f8c97e975978d45  on 2016-04-25
+#
+# The where push-down optimization from 2015-06-02 is suppose to disable
+# on aggregate subqueries.  But if the subquery is a compound where the
+# last SELECT is non-aggregate but some other SELECT is an aggregate, the
+# test is incomplete and the optimization is not properly disabled.
+# 
+# The following test cases verify that the fix works.
+#
+do_execsql_test select4-17.1 {
+  DROP TABLE IF EXISTS t1;
+  CREATE TABLE t1(a int, b int);
+  INSERT INTO t1 VALUES(1,2),(1,18),(2,19);
+  SELECT x, y FROM (
+    SELECT 98 AS x, 99 AS y
+    UNION
+    SELECT a AS x, sum(b) AS y FROM t1 GROUP BY a
+  ) AS w WHERE y>=20
+  ORDER BY +x;
+} {1 20 98 99}
+do_execsql_test select4-17.2 {
+  SELECT x, y FROM (
+    SELECT a AS x, sum(b) AS y FROM t1 GROUP BY a
+    UNION
+    SELECT 98 AS x, 99 AS y
+  ) AS w WHERE y>=20
+  ORDER BY +x;
+} {1 20 98 99}
+do_catchsql_test select4-17.3 {
+  SELECT x, y FROM (
+    SELECT a AS x, sum(b) AS y FROM t1 GROUP BY a LIMIT 3
+    UNION
+    SELECT 98 AS x, 99 AS y
+  ) AS w WHERE y>=20
+  ORDER BY +x;
+} {1 {LIMIT clause should come after UNION not before}}
 
 finish_test