diff --git a/dlls/advpack/advpack.spec b/dlls/advpack/advpack.spec
index 2fe49fee476..53790ae0e52 100644
--- a/dlls/advpack/advpack.spec
+++ b/dlls/advpack/advpack.spec
@@ -1,4 +1,4 @@
-@ stub AddDelBackupEntry
+@ stdcall AddDelBackupEntry(str str str long)
 @ stdcall AdvInstallFile(long str str str str long long)
 @ stub CloseINFEngine
 @ stdcall DelNode(str long)
diff --git a/dlls/advpack/files.c b/dlls/advpack/files.c
index 6c2d333a696..87a88bbd5c6 100644
--- a/dlls/advpack/files.c
+++ b/dlls/advpack/files.c
@@ -31,6 +31,34 @@
 
 WINE_DEFAULT_DEBUG_CHANNEL(advpack);
 
+/***********************************************************************
+ *      AddDelBackupEntry (ADVPACK.@)
+ *
+ * Either marks the file in the file list as not existing during file
+ * save, or deletes the file entry from the INI.
+ *
+ * PARAMS
+ *   lpcszFileList  [I] NULL-separated list of filenames.
+ *   lpcszBackupDir [I] Path of the backup directory.
+ *   lpcszBaseName  [I] Basename of the backup files.
+ *   dwFlags        [I] See advpub.h.
+ *
+ * RETURNS
+ *   Success: S_OK.
+ *   Failure: E_FAIL.
+ *
+ * BUGS
+ *   Unimplemented.
+ */
+HRESULT WINAPI AddDelBackupEntry(LPCSTR lpcszFileList, LPCSTR lpcszBackupDir,
+                                 LPCSTR lpcszBaseName, DWORD dwFlags)
+{
+    FIXME("(%p, %p, %p, %ld) stub\n", lpcszFileList, lpcszBackupDir,
+          lpcszBaseName, dwFlags);
+
+    return E_FAIL;
+}
+
 /* FIXME: this is only for the local case, X:\ */
 #define ROOT_LENGTH 3
 
diff --git a/include/advpub.h b/include/advpub.h
index 34893dcefc6..f45c45e59f5 100644
--- a/include/advpub.h
+++ b/include/advpub.h
@@ -46,6 +46,10 @@ typedef struct _StrTable {
 typedef const STRTABLE CSTRTABLE;
 typedef CSTRTABLE *LPCSTRTABLE;
 
+/* Flags for AddDelBackupEntry */
+#define AADBE_ADD_ENTRY             0x01
+#define AADBE_DEL_ENTRY             0x02
+
 /* Flags for AdvInstallFile */
 #define AIF_WARNIFSKIP              0x00000001
 #define AIF_NOSKIP                  0x00000002
@@ -96,6 +100,8 @@ typedef CSTRTABLE *LPCSTRTABLE;
 #define  AFSR_USEREFCNT             IE4_USEREFCNT
 #define  AFSR_EXTRAINCREFCNT        IE4_EXTRAINCREFCNT
 
+HRESULT WINAPI AddDelBackupEntry(LPCSTR lpcszFileList, LPCSTR lpcszBackupDir,
+     LPCSTR lpcszBaseName, DWORD dwFlags);
 HRESULT WINAPI AdvInstallFile(HWND hwnd, LPCSTR lpszSourceDir,
      LPCSTR lpszSourceFile, LPCSTR lpszDestDir, LPCSTR lpszDestFile,
      DWORD dwFlags, DWORD dwReserved);