Index: src/os_win.c
==================================================================
--- src/os_win.c
+++ src/os_win.c
@@ -1087,10 +1087,11 @@
     if( aSyscall[i].pCurrent!=0 ) return aSyscall[i].zName;
   }
   return 0;
 }
 
+#ifdef SQLITE_WIN32_MALLOC
 /*
 ** If a Win32 native heap has been configured, this function will attempt to
 ** compact it.  Upon success, SQLITE_OK will be returned.  Upon failure, one
 ** of SQLITE_NOMEM, SQLITE_ERROR, or SQLITE_NOTFOUND will be returned.  The
 ** "pnLargest" argument, if non-zero, will be used to return the size of the
@@ -1142,20 +1143,30 @@
   MUTEX_LOGIC( sqlite3_mutex *pMem; )    /* The memsys static mutex */
   MUTEX_LOGIC( pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
   MUTEX_LOGIC( pMem = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM); )
   sqlite3_mutex_enter(pMaster);
   sqlite3_mutex_enter(pMem);
-  if( winMemGetOwned() && sqlite3_memory_used()==0 ){
+  winMemAssertMagic();
+  if( winMemGetHeap()!=NULL && winMemGetOwned() && sqlite3_memory_used()==0 ){
     /*
     ** At this point, there should be no outstanding memory allocations on
     ** the heap.  Also, since both the master and memsys locks are currently
     ** being held by us, no other function (i.e. from another thread) should
     ** be able to even access the heap.  Attempt to destroy and recreate our
     ** isolated Win32 native heap now.
     */
+    assert( winMemGetHeap()!=NULL );
+    assert( winMemGetOwned() );
+    assert( sqlite3_memory_used()==0 );
     winMemShutdown(winMemGetDataPtr());
+    assert( winMemGetHeap()==NULL );
+    assert( !winMemGetOwned() );
+    assert( sqlite3_memory_used()==0 );
     rc = winMemInit(winMemGetDataPtr());
+    assert( rc!=SQLITE_OK || winMemGetHeap()!=NULL );
+    assert( rc!=SQLITE_OK || winMemGetOwned() );
+    assert( rc!=SQLITE_OK || sqlite3_memory_used()==0 );
   }else{
     /*
     ** The Win32 native heap cannot be modified because it may be in use.
     */
     rc = SQLITE_BUSY;
@@ -1162,10 +1173,11 @@
   }
   sqlite3_mutex_leave(pMem);
   sqlite3_mutex_leave(pMaster);
   return rc;
 }
+#endif /* SQLITE_WIN32_MALLOC */
 
 /*
 ** This function outputs the specified (ANSI) string to the Win32 debugger
 ** (if available).
 */