Index: src/os_win.c
==================================================================
--- src/os_win.c
+++ src/os_win.c
@@ -3629,19 +3629,20 @@
 **
 **   winShmEnterMutex()
 **     assert( winShmMutexHeld() );
 **   winShmLeaveMutex()
 */
+static sqlite3_mutex *winBigLock = 0;
 static void winShmEnterMutex(void){
-  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1));
+  sqlite3_mutex_enter(winBigLock);
 }
 static void winShmLeaveMutex(void){
-  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1));
+  sqlite3_mutex_leave(winBigLock);
 }
 #ifndef NDEBUG
 static int winShmMutexHeld(void) {
-  return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1));
+  return sqlite3_mutex_held(winBigLock);
 }
 #endif
 
 /*
 ** Object used to represent a single file opened and mmapped to provide
@@ -6060,10 +6061,11 @@
 
 #if defined(SQLITE_WIN32_HAS_WIDE)
   sqlite3_vfs_register(&winLongPathNolockVfs, 0);
 #endif
 
+  winBigLock = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1);
   return SQLITE_OK;
 }
 
 int sqlite3_os_end(void){
 #if SQLITE_OS_WINRT
@@ -6070,9 +6072,10 @@
   if( sleepObj!=NULL ){
     osCloseHandle(sleepObj);
     sleepObj = NULL;
   }
 #endif
+  winBigLock = 0;
   return SQLITE_OK;
 }
 
 #endif /* SQLITE_OS_WIN */