Index: src/test_vfs.c
==================================================================
--- src/test_vfs.c
+++ src/test_vfs.c
@@ -538,10 +538,11 @@
   pFd->pShm = 0;
   pFd->pShmId = 0;
   pFd->zFilename = zName;
   pFd->pVfs = pVfs;
   pFd->pReal = (sqlite3_file *)&pFd[1];
+  memset(pTestfile, 0, sizeof(TestvfsFile));
   pTestfile->pFd = pFd;
 
   /* Evaluate the Tcl script: 
   **
   **   SCRIPT xOpen FILENAME