diff --git a/include/msi.h b/include/msi.h
index 604331a9e5f..c1ca99771a4 100644
--- a/include/msi.h
+++ b/include/msi.h
@@ -470,8 +470,8 @@ UINT WINAPI MsiEnumClientsA(LPCSTR, DWORD, LPSTR);
 UINT WINAPI MsiEnumClientsW(LPCWSTR, DWORD, LPWSTR);
 #define     MsiEnumClients WINELIB_NAME_AW(MsiEnumClients)
 
-UINT WINAPI MsiEnumClientsExA(LPCSTR, LPCSTR, DWORD, DWORD, CHAR*, MSIINSTALLCONTEXT*, LPSTR, LPDWORD);
-UINT WINAPI MsiEnumClientsExW(LPCWSTR, LPCWSTR, DWORD, DWORD, WCHAR*, MSIINSTALLCONTEXT*, LPWSTR, LPDWORD);
+UINT WINAPI MsiEnumClientsExA(LPCSTR, LPCSTR, DWORD, DWORD, CHAR[39], MSIINSTALLCONTEXT*, LPSTR, LPDWORD);
+UINT WINAPI MsiEnumClientsExW(LPCWSTR, LPCWSTR, DWORD, DWORD, WCHAR[39], MSIINSTALLCONTEXT*, LPWSTR, LPDWORD);
 #define     MsiEnumClientsEx WINELIB_NAME_AW(MsiEnumClientsEx)
 
 UINT WINAPI MsiOpenPackageA(LPCSTR, MSIHANDLE*);