Index: src/bitvec.c
==================================================================
--- src/bitvec.c
+++ src/bitvec.c
@@ -168,11 +168,11 @@
 */
 int sqlite3BitvecSet(Bitvec *p, u32 i){
   u32 h;
   if( p==0 ) return SQLITE_OK;
   assert( i>0 );
-  /* assert( i<=p->iSize ); */
+  assert( i<=p->iSize );
   if( i>p->iSize ){
     sqlite3_log(SQLITE_ERROR, 
         "Bitvec: setting bit %d of bitvec size %d\n", (int)i, (int)p->iSize
     );
   }

Index: src/btree.c
==================================================================
--- src/btree.c
+++ src/btree.c
@@ -4127,14 +4127,15 @@
         ** of the database file (i.e. free-list entries). */
         if( rc==SQLITE_OK ){
           assert( nCurrent!=PENDING_BYTE_PAGE(pBt) );
           sqlite3PagerSetDbsize(pBt->pPager, nCurrent);
           nFree = get4byte(&p1[36]);
-          nFin = MAX(nCurrent-nFree, nHPage);
+          nFin = nCurrent-nFree;
           if( nCurrent>PENDING_BYTE_PAGE(pBt) && nFin<=PENDING_BYTE_PAGE(pBt) ){
             nFin--;
           }
+          nFin = MAX(nFin, nHPage);
           rc = btreeRelocateRange(pBt, nFin+1, nCurrent, 0);
         }
 
         put4byte(&p1[28], nFin);
       }

Index: test/concurrent2.test
==================================================================
--- test/concurrent2.test
+++ test/concurrent2.test
@@ -574,8 +574,50 @@
     sql1 { PRAGMA wal_checkpoint }
     sql2 { INSERT INTO t1 VALUES(3) }
     code2 { sqlite3_wal_info db2 main }
   } {0 1}
 }
+
+reset_db
+do_execsql_test 12.0 {
+  PRAGMA journal_mode = wal;
+  CREATE TABLE tx(a INTEGER PRIMARY KEY, b);
+} {wal}
+do_test 12.1 {
+  for {set i 0} {$i < 50} {incr i} {
+    execsql {
+      BEGIN CONCURRENT;
+      INSERT INTO tx(b) VALUES( randomblob( 1200 ) );
+      COMMIT;
+    }
+  }
+  execsql { PRAGMA page_size }
+} {1024}
+do_execsql_test 12.2 {
+  DELETE FROM tx;
+}
+do_test 12.3 {
+  for {set i 0} {$i < 50} {incr i} {
+    execsql {
+      BEGIN CONCURRENT;
+      INSERT INTO tx(b) VALUES( randomblob( 1200 ) );
+      COMMIT;
+    }
+  }
+  execsql { PRAGMA page_size }
+} {1024}
+do_execsql_test 12.4 {
+  DELETE FROM tx;
+}
+do_test 12.5 {
+  execsql { BEGIN CONCURRENT }
+  for {set i 0} {$i < 5000} {incr i} {
+    execsql {
+      INSERT INTO tx(b) VALUES( randomblob( 1200 ) );
+    }
+  }
+  execsql { COMMIT }
+  execsql { PRAGMA page_size }
+} {1024}
 
 
 finish_test