diff --git a/dlls/netapi32/nbcmdqueue.c b/dlls/netapi32/nbcmdqueue.c
index de70e6bfc9c..720826d8cc8 100644
--- a/dlls/netapi32/nbcmdqueue.c
+++ b/dlls/netapi32/nbcmdqueue.c
@@ -62,6 +62,7 @@ struct NBCmdQueue *NBCmdQueueCreate(HANDLE heap)
     {
         queue->heap = heap;
         InitializeCriticalSection(&queue->cs);
+        queue->cs.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": NBCmdQueue.cs");
         queue->head = NULL;
     }
     return queue;
@@ -193,6 +194,7 @@ void NBCmdQueueDestroy(struct NBCmdQueue *queue)
     if (queue)
     {
         NBCmdQueueCancelAll(queue);
+        queue->cs.DebugInfo->Spare[0] = 0;
         DeleteCriticalSection(&queue->cs);
         HeapFree(queue->heap, 0, queue);
     }
diff --git a/dlls/netapi32/nbnamecache.c b/dlls/netapi32/nbnamecache.c
index 82c10a9013b..b9ed15911c7 100644
--- a/dlls/netapi32/nbnamecache.c
+++ b/dlls/netapi32/nbnamecache.c
@@ -104,6 +104,7 @@ struct NBNameCache *NBNameCacheCreate(HANDLE heap, DWORD entryExpireTimeMS)
     {
         cache->heap = heap;
         InitializeCriticalSection(&cache->cs);
+        cache->cs.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": NBNameCache.cs");
         cache->entryExpireTimeMS = entryExpireTimeMS;
         cache->head = NULL;
     }
@@ -204,6 +205,7 @@ void NBNameCacheDestroy(struct NBNameCache *cache)
 {
     if (cache)
     {
+        cache->cs.DebugInfo->Spare[0] = 0;
         DeleteCriticalSection(&cache->cs);
         while (cache->head)
             NBNameCacheUnlinkNode(cache, &cache->head);
diff --git a/dlls/netapi32/nbt.c b/dlls/netapi32/nbt.c
index c09b8fa3813..27dba60a7af 100644
--- a/dlls/netapi32/nbt.c
+++ b/dlls/netapi32/nbt.c
@@ -1050,6 +1050,7 @@ static UCHAR NetBTCall(void *adapt, PNCB ncb, void **sess)
                     {
                         session->fd = fd;
                         InitializeCriticalSection(&session->cs);
+                        session->cs.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": NetBTSession.cs");
                         *sess = session;
                     }
                     else
@@ -1243,6 +1244,7 @@ static UCHAR NetBTHangup(void *adapt, void *sess)
     closesocket(session->fd);
     session->fd = INVALID_SOCKET;
     session->bytesPending = 0;
+    session->cs.DebugInfo->Spare[0] = 0;
     DeleteCriticalSection(&session->cs);
     HeapFree(GetProcessHeap(), 0, session);
 
diff --git a/dlls/netapi32/netbios.c b/dlls/netapi32/netbios.c
index c104ceae0ee..3362f03a001 100644
--- a/dlls/netapi32/netbios.c
+++ b/dlls/netapi32/netbios.c
@@ -104,6 +104,7 @@ void NetBIOSInit(void)
 {
     memset(&gNBTable, 0, sizeof(gNBTable));
     InitializeCriticalSection(&gNBTable.cs);
+    gNBTable.cs.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": NetBIOSAdapterTable.cs");
 }
 
 void NetBIOSShutdown(void)
@@ -122,6 +123,7 @@ void NetBIOSShutdown(void)
         if (gTransports[i].transport.cleanup)
             gTransports[i].transport.cleanup();
     LeaveCriticalSection(&gNBTable.cs);
+    gNBTable.cs.DebugInfo->Spare[0] = 0;
     DeleteCriticalSection(&gNBTable.cs);
     HeapFree(GetProcessHeap(), 0, gNBTable.table);
 }
@@ -210,6 +212,7 @@ BOOL NetBIOSRegisterAdapter(ULONG transport, DWORD ifIndex, void *data)
             gNBTable.table[i].impl.data = data;
             gNBTable.table[i].cmdQueue = NBCmdQueueCreate(GetProcessHeap());
             InitializeCriticalSection(&gNBTable.table[i].cs);
+            gNBTable.table[i].cs.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": NetBIOSAdapterTable.NetBIOSAdapter.cs");
             gNBTable.table[i].enabled = TRUE;
             ret = TRUE;
         }
@@ -246,6 +249,7 @@ static void nbShutdownAdapter(NetBIOSAdapter *adapter)
         if (adapter->transport->cleanupAdapter)
             adapter->transport->cleanupAdapter(adapter->impl.data);
         NBCmdQueueDestroy(adapter->cmdQueue);
+        adapter->cs.DebugInfo->Spare[0] = 0;
         DeleteCriticalSection(&adapter->cs);
         memset(adapter, 0, sizeof(NetBIOSAdapter));
     }