Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -2241,11 +2241,11 @@
   int tnum;                /* DB Page containing root of this index */
   LogEst szIdxRow;         /* Estimated average row size in bytes */
   u16 nKeyCol;             /* Number of columns forming the key */
   u16 nColumn;             /* Number of columns stored in the index */
   u8 onError;              /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
-  unsigned idxType:2;      /* 1==UNIQUE, 2==PRIMARY KEY, 0==CREATE INDEX */
+  unsigned idxType:2;      /* 0:Normal 1:UNIQUE, 2:PRIMARY KEY, 3:IPK */
   unsigned bUnordered:1;   /* Use this index for == or IN queries only */
   unsigned uniqNotNull:1;  /* True if UNIQUE and NOT NULL for all columns */
   unsigned isResized:1;    /* True if resizeIndexObject() has been called */
   unsigned isCovering:1;   /* True if this is a covering index */
   unsigned noSkipScan:1;   /* Do not try to use skip-scan if true */
@@ -2266,10 +2266,11 @@
 ** Allowed values for Index.idxType
 */
 #define SQLITE_IDXTYPE_APPDEF      0   /* Created using CREATE INDEX */
 #define SQLITE_IDXTYPE_UNIQUE      1   /* Implements a UNIQUE constraint */
 #define SQLITE_IDXTYPE_PRIMARYKEY  2   /* Is the PRIMARY KEY for the table */
+#define SQLITE_IDXTYPE_IPK         3   /* INTEGER PRIMARY KEY index */
 
 /* Return true if index X is a PRIMARY KEY index */
 #define IsPrimaryKeyIndex(X)  ((X)->idxType==SQLITE_IDXTYPE_PRIMARYKEY)
 
 /* Return true if index X is a UNIQUE index */

Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -2208,11 +2208,11 @@
     }
   }
   rc = whereLoopXfer(db, p, pTemplate);
   if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){
     Index *pIndex = p->u.btree.pIndex;
-    if( pIndex && pIndex->tnum==0 ){
+    if( pIndex && pIndex->idxType==SQLITE_IDXTYPE_IPK ){
       p->u.btree.pIndex = 0;
     }
   }
   return rc;
 }
@@ -2375,12 +2375,12 @@
 ** When this function is called, pBuilder->pNew->nOut contains the 
 ** number of rows expected to be visited by filtering using the nEq 
 ** terms only. If it is modified, this value is restored before this 
 ** function returns.
 **
-** If pProbe->tnum==0, that means pIndex is a fake index used for the
-** INTEGER PRIMARY KEY.
+** If pProbe->idxType==SQLITE_IDXTYPE_IPK, that means pIndex is 
+** a fake index used for the INTEGER PRIMARY KEY.
 */
 static int whereLoopAddBtreeIndex(
   WhereLoopBuilder *pBuilder,     /* The WhereLoop factory */
   struct SrcList_item *pSrc,      /* FROM clause term being analyzed */
   Index *pProbe,                  /* An index on pSrc */
@@ -2876,10 +2876,11 @@
     sPk.aiColumn = &aiColumnPk;
     sPk.aiRowLogEst = aiRowEstPk;
     sPk.onError = OE_Replace;
     sPk.pTable = pTab;
     sPk.szIdxRow = pTab->szTabRow;
+    sPk.idxType = SQLITE_IDXTYPE_IPK;
     aiRowEstPk[0] = pTab->nRowLogEst;
     aiRowEstPk[1] = 0;
     pFirst = pSrc->pTab->pIndex;
     if( pSrc->fg.notIndexed==0 ){
       /* The real indices of the table are only considered if the
@@ -2966,11 +2967,11 @@
     pNew->nOut = rSize;
     pNew->u.btree.pIndex = pProbe;
     b = indexMightHelpWithOrderBy(pBuilder, pProbe, pSrc->iCursor);
     /* The ONEPASS_DESIRED flags never occurs together with ORDER BY */
     assert( (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || b==0 );
-    if( pProbe->tnum<=0 ){
+    if( pProbe->idxType==SQLITE_IDXTYPE_IPK ){
       /* Integer primary key index */
       pNew->wsFlags = WHERE_IPK;
 
       /* Full table scan */
       pNew->iSortIdx = b ? iSortIdx : 0;

Index: test/fts3fuzz001.test
==================================================================
--- test/fts3fuzz001.test
+++ test/fts3fuzz001.test
@@ -100,11 +100,11 @@
 } {1 {database disk image is malformed}}
 do_test fts3fuzz001-120 {
   catchsql {
     INSERT INTO t1(t1) VALUES('optimize');
   }
-} {0 {}}
+} {1 {database disk image is malformed}}
 do_test fts3fuzz001-121 {
   catchsql {
     INSERT INTO t1(t1) VALUES('integrity-check');
   }
 } {1 {database disk image is malformed}}