diff --git a/reactos/dll/win32/advapi32/sec/misc.c b/reactos/dll/win32/advapi32/sec/misc.c
index bee74716d49..cac8d84d842 100644
--- a/reactos/dll/win32/advapi32/sec/misc.c
+++ b/reactos/dll/win32/advapi32/sec/misc.c
@@ -69,7 +69,9 @@ CheckNtMartaPresent(VOID)
 {
     DWORD ErrorCode;
 
-    if (NtMarta == NULL)
+    if (InterlockedCompareExchangePointer(&NtMarta,
+                                          NULL,
+                                          NULL) == NULL)
     {
         /* we're the first one trying to use ntmarta, initialize it and change
            the pointer after initialization */