diff --git a/manifest b/manifest
index f2027f792a..650ae769af 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Small\sperformance\senhancement\sfor\swhereScanInit().
-D 2021-12-02T02:22:35.475
+C Small\sperformance\soptimization\sin\ssqlite3WhereGetMask().
+D 2021-12-02T04:00:45.798
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -637,8 +637,8 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c ed0398a7adf02c31e34aada42cc86c58f413a7afe5f741a5d373ad087abde028
 F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a
 F src/walker.c f890a3298418d7cba3b69b8803594fdc484ea241206a8dfa99db6dd36f8cbb3b
-F src/where.c 36e6ce4c1dd564885f2596e2c2aab61c7a56c7f9aeae63d6bb258d1464883ad6
-F src/whereInt.h 83877a75a1bce056ea44aff02f1dfa958ad1d6038c213ddadb8652003b45151d
+F src/where.c 90903cab02f03aded5019e45cd1dec6adf307291a6af0e55fce5111e84cc9115
+F src/whereInt.h 1630d9418512b080598e9a72b8af6b8bd1b9ab13fee1458f151762b6df206791
 F src/wherecode.c 1f5b62f46d284c8886945eb7438415bc27e23e87bb60b9ee468fa6bd31268f33
 F src/whereexpr.c 17bdbf4f5b490e70a18635498f0b910a558f953a9bf80af7f19cbde6e60e6825
 F src/window.c 5d3b397b0c026d0ff5890244ac41359e524c01ae31e78782e1ff418c3e271a9e
@@ -1933,7 +1933,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P ca59533bbb7f21d7b39dee7999d3f36ac516f8c75b2203039beeb2852ada42d4
-R af3fe3cb608001edf986e30906f5d5ad
+P ed84e124c6097b756ca687ac64df7ee801d14b16c835f1a9e8b336f785157d85
+R 4968f927e754c905a194070e8df46560
 U drh
-Z e7cfc5073afcf7170a57b786bbc9a825
+Z 0a6600fef45926158d5c9c07197fe75a
diff --git a/manifest.uuid b/manifest.uuid
index 7e8fe9d6a3..3e8bb6ca63 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-ed84e124c6097b756ca687ac64df7ee801d14b16c835f1a9e8b336f785157d85
\ No newline at end of file
+7edec54ab045c0493fc5d27d47d7bf0e08d3b0b298f428646fd3f0ee24dfcade
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index 53fa001dee..a661940b39 100644
--- a/src/where.c
+++ b/src/where.c
@@ -232,13 +232,15 @@ whereOrInsert_done:
 ** iCursor is not in the set.
 */
 Bitmask sqlite3WhereGetMask(WhereMaskSet *pMaskSet, int iCursor){
-  int i;
+  int i = 0;
   assert( pMaskSet->n<=(int)sizeof(Bitmask)*8 );
-  for(i=0; i<pMaskSet->n; i++){
+  assert( pMaskSet->n>0 || pMaskSet->ix[0]<0 );
+  assert( iCursor>=-1 );
+  do{
     if( pMaskSet->ix[i]==iCursor ){
       return MASKBIT(i);
     }
-  }
+  }while( (++i)<pMaskSet->n );
   return 0;
 }
 
@@ -4926,7 +4928,8 @@ WhereInfo *sqlite3WhereBegin(
   /* Split the WHERE clause into separate subexpressions where each
   ** subexpression is separated by an AND operator.
   */
-  initMaskSet(pMaskSet);
+  pMaskSet->n = 0;
+  pMaskSet->ix[0] = -99;
   sqlite3WhereClauseInit(&pWInfo->sWC, pWInfo);
   sqlite3WhereSplit(&pWInfo->sWC, pWhere, TK_AND);
     
diff --git a/src/whereInt.h b/src/whereInt.h
index f651e790cc..217dd0ba2a 100644
--- a/src/whereInt.h
+++ b/src/whereInt.h
@@ -292,11 +292,11 @@ struct WhereScan {
   WhereClause *pWC;          /* WhereClause currently being scanned */
   const char *zCollName;     /* Required collating sequence, if not NULL */
   Expr *pIdxExpr;            /* Search for this index expression */
-  char idxaff;               /* Must match this affinity, if zCollName!=NULL */
-  unsigned char nEquiv;      /* Number of entries in aiCur[] and aiColumn[] */
-  unsigned char iEquiv;      /* Next unused slot in aiCur[] and aiColumn[] */
-  u32 opMask;                /* Acceptable operators */
   int k;                     /* Resume scanning at this->pWC->a[this->k] */
+  u32 opMask;                /* Acceptable operators */
+  char idxaff;               /* Must match this affinity, if zCollName!=NULL */
+  unsigned char iEquiv;      /* Current slot in aiCur[] and aiColumn[] */
+  unsigned char nEquiv;      /* Number of entries in aiCur[] and aiColumn[] */
   int aiCur[11];             /* Cursors in the equivalence class */
   i16 aiColumn[11];          /* Corresponding column number in the eq-class */
 };
@@ -377,11 +377,6 @@ struct WhereMaskSet {
   int ix[BMS];                  /* Cursor assigned to each bit */
 };
 
-/*
-** Initialize a WhereMaskSet object
-*/
-#define initMaskSet(P)  (P)->n=0
-
 /*
 ** This object is a convenience wrapper holding all information needed
 ** to construct WhereLoop objects for a particular query.