diff --git a/reactos/dll/win32/msi/msiserver.idl b/reactos/dll/win32/msi/msiserver.idl
index 2189fc4c9af..ac442dbd076 100644
--- a/reactos/dll/win32/msi/msiserver.idl
+++ b/reactos/dll/win32/msi/msiserver.idl
@@ -29,6 +29,7 @@ typedef int INSTALLMESSAGE;
 typedef int MSICONDITION;
 typedef int MSIRUNMODE;
 typedef int INSTALLSTATE;
+typedef WORD LANGID;
 cpp_quote("#endif")
 
 [
diff --git a/reactos/include/psdk/msi.h b/reactos/include/psdk/msi.h
index 5564fcd1502..a6a5f3d552c 100644
--- a/reactos/include/psdk/msi.h
+++ b/reactos/include/psdk/msi.h
@@ -27,7 +27,7 @@ extern "C" {
 #include <wincrypt.h>
 #endif
 
-typedef unsigned long MSIHANDLE;
+typedef ULONG MSIHANDLE;
 
 typedef enum tagINSTALLSTATE
 {
diff --git a/reactos/include/psdk/msiquery.h b/reactos/include/psdk/msiquery.h
index fa42f17ec47..6a1bfa43787 100644
--- a/reactos/include/psdk/msiquery.h
+++ b/reactos/include/psdk/msiquery.h
@@ -47,6 +47,7 @@ typedef enum tagMSICOSTTREE
 
 typedef enum tagMSIMODIFY
 {
+    MSIMODIFY_SEEK = -1,
     MSIMODIFY_REFRESH = 0,
     MSIMODIFY_INSERT = 1,
     MSIMODIFY_UPDATE = 2,