Index: ext/misc/json1.c
==================================================================
--- ext/misc/json1.c
+++ ext/misc/json1.c
@@ -2502,18 +2502,18 @@
     { "json_tree",            &jsonTreeModule               },
   };
 #endif
   for(i=0; i<sizeof(aFunc)/sizeof(aFunc[0]) && rc==SQLITE_OK; i++){
     rc = sqlite3_create_function(db, aFunc[i].zName, aFunc[i].nArg,
-                        SQLITE_UTF8 | SQLITE_DETERMINISTIC | SQLITE_SUBTYPE, 
-                        (void*)&aFunc[i].flag,
-                        aFunc[i].xFunc, 0, 0);
+                                 SQLITE_UTF8 | SQLITE_DETERMINISTIC,
+                                 (void*)&aFunc[i].flag,
+                                 aFunc[i].xFunc, 0, 0);
   }
 #ifndef SQLITE_OMIT_WINDOWFUNC
   for(i=0; i<sizeof(aAgg)/sizeof(aAgg[0]) && rc==SQLITE_OK; i++){
     rc = sqlite3_create_window_function(db, aAgg[i].zName, aAgg[i].nArg,
-                                 SQLITE_UTF8 | SQLITE_DETERMINISTIC, 0,
+                SQLITE_SUBTYPE | SQLITE_UTF8 | SQLITE_DETERMINISTIC, 0,
                                  aAgg[i].xStep, aAgg[i].xFinal,
                                  aAgg[i].xValue, jsonGroupInverse, 0);
   }
 #endif
 #ifndef SQLITE_OMIT_VIRTUALTABLE

Index: src/sqlite.h.in
==================================================================
--- src/sqlite.h.in
+++ src/sqlite.h.in
@@ -4986,13 +4986,17 @@
 ** deterministic, for example, but randomblob() is not.
 **
 ** The SQLITE_DIRECTONLY flag means that the function may only be invoked
 ** from top-level SQL, and cannot be used in VIEWs or TRIGGERs.
 **
-** The SQLITE_SUBTYPE flag indicates to SQLite that the function may call
-** [sqlite3_result_subtype()] in order to configure its return value with
-** a sub-type.
+** The SQLITE_SUBTYPE flag indicates to SQLite that a function may call
+** [sqlite3_value_subtype()] to inspect the sub-types of its arguments.
+** Specifying this flag makes no difference for scalar or aggregate user
+** functions. However, if it is not specified for a user-defined window
+** function, then any sub-types belonging to arguments passed to the window
+** function may be discarded before the window function is called (i.e.
+** sqlite3_value_subtype() will always return 0).
 */
 #define SQLITE_DETERMINISTIC    0x000000800
 #define SQLITE_DIRECTONLY       0x000080000
 #define SQLITE_SUBTYPE          0x000100000
 

Index: src/window.c
==================================================================
--- src/window.c
+++ src/window.c
@@ -866,36 +866,10 @@
   (void)sqlite3WalkExprList(&sWalker, pEList);
 
   *ppSub = sRewrite.pSub;
 }
 
-/*
-** Return true if the top-level of list pList contains an SQL function 
-** with the SQLITE_FUNC_SUBTYPE flag set. Return false otherwise.
-*/
-int exprListContainsSubtype(Parse *pParse, ExprList *pList){
-  if( pList ){
-    sqlite3 *db = pParse->db;
-    int i;
-    for(i=0; i<pList->nExpr; i++){
-      Expr *p = pList->a[i].pExpr;
-      if( p->op==TK_FUNCTION ){
-        FuncDef *pDef;
-        int nArg = 0;
-        if( !ExprHasProperty(p, EP_TokenOnly) && p->x.pList ){
-          nArg = p->x.pList->nExpr;
-        }
-        pDef = sqlite3FindFunction(db, p->u.zToken, nArg, db->enc, 0);
-        if( pDef && (pDef->funcFlags & SQLITE_FUNC_SUBTYPE) ){
-          return 1;
-        }
-      }
-    }
-  }
-  return 0;
-}
-
 /*
 ** Append a copy of each expression in expression-list pAppend to
 ** expression list pList. Return a pointer to the result list.
 */
 static ExprList *exprListAppendList(
@@ -990,11 +964,11 @@
     ** sub-select expression list. Also allocate two registers for each
     ** window function - one for the accumulator, another for interim
     ** results.  */
     for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
       ExprList *pArgs = pWin->pOwner->x.pList;
-      if( exprListContainsSubtype(pParse, pArgs) ){
+      if( pWin->pFunc->funcFlags & SQLITE_FUNC_SUBTYPE ){
         selectWindowRewriteEList(pParse, pMWin, pSrc, pArgs, pTab, &pSublist);
         pWin->iArgCol = (pSublist ? pSublist->nExpr : 0);
         pWin->bExprArgs = 1;
       }else{
         pWin->iArgCol = (pSublist ? pSublist->nExpr : 0);