diff --git a/dll/win32/msgina/msgina.spec b/dll/win32/msgina/msgina.spec
index 1d235ae5f62..53de1e66eaf 100644
--- a/dll/win32/msgina/msgina.spec
+++ b/dll/win32/msgina/msgina.spec
@@ -6,7 +6,7 @@
 6 stub -noname ShellEnableFriendlyUI    ; (long)
 7 stub -noname ShellEnableMultipleUsers ; (long)
 8 stub -noname ShellEnableRemoteConnections ; (long)
-9 stub -noname ShellTurnOffDialog ; (long)
+9 stdcall -noname ShellTurnOffDialog(ptr)
 10 stub -noname ShellIsMultipleUsersEnabled ; ()
 11 stub -noname ShellACPIPowerButtonPressed ; (long long long)
 12 stub -noname ShellIsSingleUserNoPassword ; (wstr wstr)
diff --git a/dll/win32/msgina/shutdown.c b/dll/win32/msgina/shutdown.c
index bc6e97949d6..dd8591b4a7a 100644
--- a/dll/win32/msgina/shutdown.c
+++ b/dll/win32/msgina/shutdown.c
@@ -825,3 +825,14 @@ ShellShutdownDialog(
 
     return 0;
 }
+
+/*
+ * NOTES:
+ * - Undocumented, called from MS shell32.dll to show the turn off dialog.
+ * - Seems to have the same purpose as ShellShutdownDialog.
+ */
+DWORD WINAPI
+ShellTurnOffDialog(HWND hWnd)
+{
+    return ShellShutdownDialog(hWnd, NULL, FALSE);
+}