diff --git a/include/inseng.idl b/include/inseng.idl
index 7b9d0e778fd..8a3f4c4d270 100644
--- a/include/inseng.idl
+++ b/include/inseng.idl
@@ -20,6 +20,107 @@
 #define threading(model)
 #endif
 
+cpp_quote("#if 0")
+import "unknwn.idl";
+cpp_quote("#endif")
+
+interface IStream;
+
+/* FIXME: Add full declarations. */
+interface ICifComponent;
+interface IEnumCifComponents;
+interface ICifGroup;
+interface IEnumCifGroups;
+interface ICifMode;
+interface IEnumCifModes;
+
+typedef struct {
+    DWORD cbSize;
+    DWORD dwInstallSize;
+    DWORD dwWinDriveSize;
+    DWORD dwDownloadSize;
+    DWORD dwDependancySize;
+    DWORD dwInstallDriveReq;
+    DWORD dwWinDriveReq;
+    DWORD dwDownloadDriveReq;
+    char chWinDrive;
+    char chInstallDrive;
+    char chDownloadDrive;
+    DWORD dwTotalDownloadSize;
+} COMPONENT_SIZES;
+
+[
+    uuid(6e449688-c509-11cf-aafa-00aa00b6015c),
+    local
+]
+interface ICifFile : IUnknown
+{
+    HRESULT EnumComponents(IEnumCifComponents **enum_components, DWORD filter, void *pv);
+    HRESULT FindComponent(const char *id, ICifComponent **p);
+    HRESULT EnumGroups(IEnumCifGroups **enum_groups, DWORD filter, void *pv);
+    HRESULT FindGroup(const char *id, ICifGroup **p);
+    HRESULT EnumModes(IEnumCifModes **cuf_modes, DWORD filter, void *pv);
+    HRESULT FindMode(const char *id, ICifMode **p);
+    HRESULT GetDescription(char *desc, DWORD size);
+    HRESULT GetDetDlls(char **dlls, DWORD size);
+}
+
+[
+    uuid(6e449685-c509-11cf-aafa-00aa00b6015c),
+    local
+]
+interface IInstallEngineCallback : IUnknown
+{
+   HRESULT OnEngineStatusChange(DWORD status, DWORD substatus);
+   HRESULT OnStartInstall(DWORD dl_size, DWORD install_size);
+   HRESULT OnStartComponent(const char *id, DWORD dl_size, DWORD install_size, const char *string);
+   HRESULT OnComponentProgress(const char *id, DWORD phrase, const char *string,
+           const char *msg_string, ULONG progress, ULONG max);
+   HRESULT OnStopComponent(const char *id, HRESULT error, DWORD phrase, const char *string, DWORD status);
+   HRESULT OnStopInstall(HRESULT error, const char *error_string, DWORD status);
+   HRESULT OnEngineProblem(DWORD problem, LPDWORD action);
+}
+
+[
+    uuid(6e449684-c509-11cf-aafa-00aa00b6015c),
+    local
+]
+interface IInstallEngine : IUnknown
+{
+   HRESULT GetEngineStatus(DWORD *status);
+   HRESULT SetCifFile(const char *cab_name, const char *cif_name);
+   HRESULT DownloadComponents(DWORD flags);
+   HRESULT InstallComponents(DWORD flags);
+   HRESULT EnumInstallIDs(UINT index, char **id);
+   HRESULT EnumDownloadIDs(UINT index, char **id);
+   HRESULT IsComponentInstalled(const char *id, DWORD *status);
+   HRESULT RegisterInstallEngineCallback(IInstallEngineCallback *callback);
+   HRESULT UnregisterInstallEngineCallback();
+   HRESULT SetAction(const char *id, DWORD action, DWORD priority);
+   HRESULT GetSizes(const char *id, COMPONENT_SIZES *sizes);
+   HRESULT LaunchExtraCommand(const char *inf_name, const char *section);
+   HRESULT GetDisplayName(const char *id, const char *name);
+   HRESULT SetBaseUrl(const char *base_name);
+   HRESULT SetDownloadDir(const char *download_dir);
+   HRESULT SetInstallDrive(char drive);
+   HRESULT SetInstallOptions(DWORD flags);
+   HRESULT SetHWND(HWND hwnd);
+   HRESULT SetIStream(IStream *stream);
+   HRESULT Abort(DWORD flags);
+   HRESULT Suspend();
+   HRESULT Resume();
+}
+
+[
+    uuid(6e449689-c509-11cf-aafa-00aa00b6015c),
+    local
+]
+interface IInstallEngine2 : IInstallEngine
+{
+    HRESULT SetLocalCif(const char *cif);
+    HRESULT GetICifFile(ICifFile **cif_file);
+}
+
 [
     helpstring("Microsoft Active Setup Engine"),
     threading(apartment),