diff --git a/.gitignore b/.gitignore
index fdfe55be91d..d1090c1bc77 100644
--- a/.gitignore
+++ b/.gitignore
@@ -240,6 +240,7 @@ include/wine/itss.h
 include/wine/svcctl.h
 include/wine/wined3d.h
 include/wine/winedxgi.h
+include/winsxs.h
 include/wtypes.h
 include/wuapi.h
 include/xmldom.h
diff --git a/include/Makefile.in b/include/Makefile.in
index d112efaa784..733e4cc4440 100644
--- a/include/Makefile.in
+++ b/include/Makefile.in
@@ -96,6 +96,7 @@ PUBLIC_IDL_H_SRCS = \
 	wincodec.idl \
 	wine/itss.idl \
 	wine/svcctl.idl \
+	winsxs.idl \
 	wtypes.idl \
 	wuapi.idl \
 	xmldom.idl \
diff --git a/include/winsxs.idl b/include/winsxs.idl
new file mode 100644
index 00000000000..c2c38f2a6bf
--- /dev/null
+++ b/include/winsxs.idl
@@ -0,0 +1,101 @@
+/*
+ * Copyright 2010 Hans Leidekker for CodeWeavers
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+import "objidl.idl";
+
+interface IAssemblyCache;
+interface IAssemblyCacheItem;
+
+typedef struct _FUSION_INSTALL_REFERENCE_
+{
+    DWORD   cbSize;
+    DWORD   dwFlags;
+    GUID    guidScheme;
+    LPCWSTR szIdentifier;
+    LPCWSTR szNonCannonicalData;
+} FUSION_INSTALL_REFERENCE, *LPFUSION_INSTALL_REFERENCE;
+
+typedef struct _ASSEMBLY_INFO
+{
+    ULONG          cbAssemblyInfo;
+    DWORD          dwAssemblyFlags;
+    ULARGE_INTEGER uliAssemblySizeInKB;
+    LPWSTR         pszCurrentAssemblyPathBuf;
+    ULONG          cchBuf;
+} ASSEMBLY_INFO;
+
+typedef const struct _FUSION_INSTALL_REFERENCE_ *LPCFUSION_INSTALL_REFERENCE;
+
+[
+    object,
+    uuid(e707dcde-d1cd-11d2-bab9-00c04f8eceae),
+    pointer_default(unique),
+    local
+]
+interface IAssemblyCache : IUnknown
+{
+    HRESULT UninstallAssembly(
+        [in] DWORD flags,
+        [in] LPCWSTR name,
+        [in] LPCFUSION_INSTALL_REFERENCE ref,
+        [out, optional] ULONG *disp);
+
+    HRESULT QueryAssemblyInfo(
+        [in] DWORD flags,
+        [in] LPCWSTR name,
+        [in, out] ASSEMBLY_INFO *info);
+
+    HRESULT CreateAssemblyCacheItem(
+        [in] DWORD flags,
+        [in] PVOID reserved,
+        [out] IAssemblyCacheItem **item,
+        [in, optional] LPCWSTR name);
+
+    HRESULT Reserved(
+        [out] IUnknown **reserved);
+
+    HRESULT InstallAssembly(
+        [in] DWORD flags,
+        [in] LPCWSTR path,
+        [in] LPCFUSION_INSTALL_REFERENCE ref);
+}
+
+[
+    object,
+    uuid(9e3aaeb4-d1cd-11d2-bab9-00c04f8eceae),
+    pointer_default(unique),
+    local
+]
+interface IAssemblyCacheItem : IUnknown
+{
+    HRESULT CreateStream(
+        [in] DWORD flags,
+        [in] LPCWSTR name,
+        [in] DWORD format,
+        [in] DWORD format_flags,
+        [out] IStream **stream,
+        [in, optional] ULARGE_INTEGER *max_size);
+
+    HRESULT Commit(
+        [in] DWORD flags,
+        [out, optional] ULONG *disp);
+
+    HRESULT AbortItem();
+}
+
+cpp_quote("HRESULT WINAPI CreateAssemblyCache(IAssemblyCache**,DWORD);")