diff --git a/tst/memfs/memfs.cpp b/tst/memfs/memfs.cpp
index 697893f8..06ebf2bb 100644
--- a/tst/memfs/memfs.cpp
+++ b/tst/memfs/memfs.cpp
@@ -192,7 +192,7 @@ typedef struct _MEMFS_FILE_NODE
     SIZE_T ReparseDataSize;
     PVOID ReparseData;
 #endif
-    ULONG RefCount;
+    volatile LONG RefCount;
 #if defined(MEMFS_NAMED_STREAMS)
     struct _MEMFS_FILE_NODE *MainFileNode;
 #endif
@@ -260,13 +260,13 @@ VOID MemfsFileNodeDelete(MEMFS_FILE_NODE *FileNode)
 static inline
 VOID MemfsFileNodeReference(MEMFS_FILE_NODE *FileNode)
 {
-    FileNode->RefCount++;
+    InterlockedIncrement(&FileNode->RefCount);
 }
 
 static inline
 VOID MemfsFileNodeDereference(MEMFS_FILE_NODE *FileNode)
 {
-    if (0 == --FileNode->RefCount)
+    if (0 == InterlockedDecrement(&FileNode->RefCount))
         MemfsFileNodeDelete(FileNode);
 }
 
@@ -850,14 +850,18 @@ static NTSTATUS Overwrite(FSP_FILE_SYSTEM *FileSystem,
     NTSTATUS Result;
 
 #if defined(MEMFS_NAMED_STREAMS)
-    MEMFS_FILE_NODE_MAP_ENUM_CONTEXT Context = { FALSE };
+    MEMFS_FILE_NODE_MAP_ENUM_CONTEXT Context = { TRUE };
     ULONG Index;
 
     MemfsFileNodeMapEnumerateNamedStreams(Memfs->FileNodeMap, FileNode,
         MemfsFileNodeMapEnumerateFn, &Context);
     for (Index = 0; Context.Count > Index; Index++)
-        if (1 >= Context.FileNodes[Index]->RefCount)
+    {
+        LONG RefCount = Context.FileNodes[Index]->RefCount;
+        MemoryBarrier();
+        if (2 >= RefCount)
             MemfsFileNodeMapRemove(Memfs->FileNodeMap, Context.FileNodes[Index]);
+    }
     MemfsFileNodeMapEnumerateFree(&Context);
 #endif