Index: src/pager.c
==================================================================
--- src/pager.c
+++ src/pager.c
@@ -2475,24 +2475,25 @@
   
   if( isOpen(pPager->fd) 
    && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN) 
   ){
     i64 currentSize, newSize;
+    int szPage = pPager->pageSize;
     assert( pPager->eLock==EXCLUSIVE_LOCK );
     /* TODO: Is it safe to use Pager.dbFileSize here? */
     rc = sqlite3OsFileSize(pPager->fd, &currentSize);
-    newSize = pPager->pageSize*(i64)nPage;
+    newSize = szPage*(i64)nPage;
     if( rc==SQLITE_OK && currentSize!=newSize ){
       if( currentSize>newSize ){
         rc = sqlite3OsTruncate(pPager->fd, newSize);
       }else{
         char *pTmp = pPager->pTmpSpace;
-        memset(pTmp, 0, pPager->pageSize);
-        while( currentSize<newSize ){
-          rc = sqlite3OsWrite(pPager->fd, pTmp, pPager->pageSize, currentSize);
-          currentSize += pPager->pageSize;
-        }
+        memset(pTmp, 0, szPage);
+        testcase( (newSize-szPage) <  currentSize );
+        testcase( (newSize-szPage) == currentSize );
+        testcase( (newSize-szPage) >  currentSize );
+        rc = sqlite3OsWrite(pPager->fd, pTmp, szPage, newSize-szPage);
       }
       if( rc==SQLITE_OK ){
         pPager->dbFileSize = nPage;
       }
     }