Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -825,11 +825,11 @@
   int flags;                    /* Miscellaneous flags. See below */
   i64 lastRowid;                /* ROWID of most recent insert (see above) */
   unsigned int openFlags;       /* Flags passed to sqlite3_vfs.xOpen() */
   int errCode;                  /* Most recent error code (SQLITE_*) */
   int errMask;                  /* & result codes with this before returning */
-  u16 dbOptFlags;               /* Flags to enable/disable optimizations */
+  u8 dbOptFlags;                /* Flags to enable/disable optimizations */
   u8 autoCommit;                /* The auto-commit flag. */
   u8 temp_store;                /* 1: file 2: memory 0: default */
   u8 mallocFailed;              /* True if we have seen a malloc failure */
   u8 dfltLockMode;              /* Default locking-mode for attached dbs */
   signed char nextAutovac;      /* Autovac setting after VACUUM if >=0 */
@@ -969,13 +969,12 @@
 #define SQLITE_GroupByOrder   0x0004   /* GROUPBY cover of ORDERBY */
 #define SQLITE_FactorOutConst 0x0008   /* Constant factoring */
 #define SQLITE_IdxRealAsInt   0x0010   /* Store REAL as INT in indices */
 #define SQLITE_DistinctOpt    0x0020   /* DISTINCT using indexes */
 #define SQLITE_CoverIdxScan   0x0040   /* Covering index scans */
-#define SQLITE_OrderByIdx     0x0180   /* ORDER BY using indices */
-#define SQLITE_OrderByIdxJoin 0x0100   /* ORDER BY of joins via index */
-#define SQLITE_AllOpts        0x01ff   /* All optimizations */
+#define SQLITE_OrderByIdxJoin 0x0080   /* ORDER BY of joins via index */
+#define SQLITE_AllOpts        0x00ff   /* All optimizations */
 
 /*
 ** Macros for testing whether or not optimizations are enabled or disabled.
 */
 #ifndef SQLITE_OMIT_BUILTIN_TEST

Index: src/test1.c
==================================================================
--- src/test1.c
+++ src/test1.c
@@ -5939,11 +5939,10 @@
     { "groupby-order",    SQLITE_GroupByOrder   },
     { "factor-constants", SQLITE_FactorOutConst },
     { "real-as-int",      SQLITE_IdxRealAsInt   },
     { "distinct-opt",     SQLITE_DistinctOpt    },
     { "cover-idx-scan",   SQLITE_CoverIdxScan   },
-    { "order-by-idx",     SQLITE_OrderByIdx     },
     { "order-by-idx-join",SQLITE_OrderByIdxJoin },
   };
 
   if( objc!=4 ){
     Tcl_WrongNumArgs(interp, 1, objv, "DB OPT BOOLEAN");

Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -1645,11 +1645,10 @@
   sqlite3 *db = pParse->db;     /* Database connection */
   int nPriorSat;                /* ORDER BY terms satisfied by outer loops */
   int seenRowid = 0;            /* True if an ORDER BY rowid term is seen */
   int nEqOneRow;                /* Idx columns that ref unique values */
 
-  if( OptimizationDisabled(db, SQLITE_OrderByIdx) ) return 0;
   if( p->i==0 ){
     nPriorSat = 0;
     nEqOneRow = nEqCol;
   }else{
     if( OptimizationDisabled(db, SQLITE_OrderByIdxJoin) ) return 0;
@@ -3152,10 +3151,11 @@
           /* "x IN (value, value, ...)" */
           nInMul *= pExpr->x.pList->nExpr;
         }
       }else if( pTerm->eOperator & WO_ISNULL ){
         wsFlags |= WHERE_COLUMN_NULL;
+        if( nEq==nOrdered ) nOrdered++;
       }else if( bSort && nEq==nOrdered && isOrderedTerm(p, pTerm, &bRev) ){
         nOrdered++;
       }
 #ifdef SQLITE_ENABLE_STAT3
       if( nEq==0 && pProbe->aSample ) pFirstTerm = pTerm;
@@ -3214,11 +3214,11 @@
                               wsFlags, bRev&1, &bRev);
       if( nOrderBy==nOBSat ){
         bSort = 0;
         wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_ORDERBY;
       }
-      if( bRev ) wsFlags |= WHERE_REVERSE;
+      if( bRev & 1 ) wsFlags |= WHERE_REVERSE;
     }
 
     /* If there is a DISTINCT qualifier and this index will scan rows in
     ** order of the DISTINCT expressions, clear bDist and set the appropriate
     ** flags in wsFlags. */

Index: test/collate4.test
==================================================================
--- test/collate4.test
+++ test/collate4.test
@@ -387,11 +387,11 @@
     }
     count {
       SELECT a FROM collate4t1 WHERE a IN (SELECT * FROM collate4t2)
        ORDER BY rowid
     }
-  } {a A 5}
+  } {a A 6}
   do_test collate4-2.1.8 {
     count {
       SELECT a FROM collate4t1 WHERE a IN ('z', 'a');
     }
   } {a A 5}

Index: test/where.test
==================================================================
--- test/where.test
+++ test/where.test
@@ -381,11 +381,11 @@
   } {1 0 4 2 1 9 3 1 16 102}
   do_test where-5.3 {
     count {
       SELECT * FROM t1 WHERE w IN (-1,1,2,3) order by 1;
     }
-  } {1 0 4 2 1 9 3 1 16 13}
+  } {1 0 4 2 1 9 3 1 16 14}
   do_test where-5.4 {
     count {
       SELECT * FROM t1 WHERE w+0 IN (-1,1,2,3) order by 1;
     }
   } {1 0 4 2 1 9 3 1 16 102}