diff --git a/reactos/include/ndk/psfuncs.h b/reactos/include/ndk/psfuncs.h
index 979655a8d06..8f259cb9b89 100644
--- a/reactos/include/ndk/psfuncs.h
+++ b/reactos/include/ndk/psfuncs.h
@@ -326,13 +326,12 @@ NtAlertResumeThread(
     _Out_opt_ PULONG SuspendCount
 );
 
-typedef ULONG APPHELPCACHESERVICECLASS;
 NTSYSCALLAPI
 NTSTATUS
 NTAPI
 NtApphelpCacheControl(
     _In_ APPHELPCACHESERVICECLASS Service,
-    _In_ PVOID ServiceData
+    _In_opt_ PAPPHELP_CACHE_SERVICE_LOOKUP ServiceData
 );
 
 NTSYSCALLAPI
diff --git a/reactos/include/ndk/pstypes.h b/reactos/include/ndk/pstypes.h
index d8f1e2329b4..c3ca39a85ac 100644
--- a/reactos/include/ndk/pstypes.h
+++ b/reactos/include/ndk/pstypes.h
@@ -810,6 +810,29 @@ typedef struct _PROCESS_FOREGROUND_BACKGROUND
     BOOLEAN Foreground;
 } PROCESS_FOREGROUND_BACKGROUND, *PPROCESS_FOREGROUND_BACKGROUND;
 
+//
+// Apphelp SHIM Cache
+//
+typedef enum _APPHELPCACHESERVICECLASS
+{
+    ApphelpCacheServiceLookup = 0,
+    ApphelpCacheServiceRemove = 1,
+    ApphelpCacheServiceUpdate = 2,
+    ApphelpCacheServiceFlush = 3,
+    ApphelpCacheServiceDump = 4,
+
+    ApphelpDBGReadRegistry = 0x100,
+    ApphelpDBGWriteRegistry = 0x101,
+} APPHELPCACHESERVICECLASS;
+
+
+typedef struct _APPHELP_CACHE_SERVICE_LOOKUP
+{
+    UNICODE_STRING ImageName;
+    HANDLE ImageHandle;
+} APPHELP_CACHE_SERVICE_LOOKUP, *PAPPHELP_CACHE_SERVICE_LOOKUP;
+
+
 //
 // Thread Information Structures for NtQueryProcessInformation
 //