diff --git a/reactos/dll/win32/samlib/samlib.c b/reactos/dll/win32/samlib/samlib.c
index 56071964299..000fa183714 100644
--- a/reactos/dll/win32/samlib/samlib.c
+++ b/reactos/dll/win32/samlib/samlib.c
@@ -721,6 +721,22 @@ SamGetAliasMembership(IN SAM_HANDLE DomainHandle,
 }
 
 
+NTSTATUS
+NTAPI
+SamGetCompatibilityMode(IN SAM_HANDLE ObjectHandle,
+                        OUT PULONG Mode)
+{
+    TRACE("(%p %p)\n", ObjectHandle, Mode);
+
+    if (Mode == NULL)
+        return STATUS_INVALID_PARAMETER;
+
+    *Mode = SAM_SID_COMPATIBILITY_ALL;
+
+    return STATUS_SUCCESS;
+}
+
+
 NTSTATUS
 NTAPI
 SamGetGroupsForUser(IN SAM_HANDLE UserHandle,
diff --git a/reactos/dll/win32/samlib/samlib.spec b/reactos/dll/win32/samlib/samlib.spec
index 0176a0c0a68..94b0b01cf1d 100644
--- a/reactos/dll/win32/samlib/samlib.spec
+++ b/reactos/dll/win32/samlib/samlib.spec
@@ -20,7 +20,7 @@
 @ stdcall SamEnumerateUsersInDomain(ptr ptr long ptr long ptr)
 @ stdcall SamFreeMemory(ptr)
 @ stdcall SamGetAliasMembership(ptr long ptr ptr ptr)
-@ stub SamGetCompatibilityMode
+@ stdcall SamGetCompatibilityMode(ptr ptr)
 @ stub SamGetDisplayEnumerationIndex
 @ stdcall SamGetGroupsForUser(ptr ptr ptr)
 @ stdcall SamGetMembersInAlias(ptr ptr ptr)