diff --git a/dlls/ntdll/unix/loader.c b/dlls/ntdll/unix/loader.c
index f5135a19f40..f1a2b9f5a79 100644
--- a/dlls/ntdll/unix/loader.c
+++ b/dlls/ntdll/unix/loader.c
@@ -1141,7 +1141,7 @@ static NTSTATUS CDECL init_unix_lib( void *module, DWORD reason, const void *ptr
 /***********************************************************************
  *           __wine_unix_call
  */
-NTSTATUS CDECL __wine_unix_call( UINT64 handle, unsigned int code, void *args )
+NTSTATUS CDECL __wine_unix_call( unixlib_handle_t handle, unsigned int code, void *args )
 {
     return ((unixlib_entry_t*)(UINT_PTR)handle)[code]( args );
 }
diff --git a/dlls/ntdll/unix/virtual.c b/dlls/ntdll/unix/virtual.c
index 3532f5c8746..372447eb8af 100644
--- a/dlls/ntdll/unix/virtual.c
+++ b/dlls/ntdll/unix/virtual.c
@@ -4345,14 +4345,14 @@ NTSTATUS WINAPI NtQueryVirtualMemory( HANDLE process, LPCVOID addr,
 
         case MemoryWineUnixFuncs:
         case MemoryWineUnixWow64Funcs:
-            if (len != sizeof(UINT64)) return STATUS_INFO_LENGTH_MISMATCH;
+            if (len != sizeof(unixlib_handle_t)) return STATUS_INFO_LENGTH_MISMATCH;
             if (process == GetCurrentProcess())
             {
                 void *module = (void *)addr;
                 void *funcs = NULL;
 
                 status = get_builtin_unix_funcs( module, info_class == MemoryWineUnixWow64Funcs, &funcs );
-                if (!status) *(UINT64 *)buffer = (UINT_PTR)funcs;
+                if (!status) *(unixlib_handle_t *)buffer = (UINT_PTR)funcs;
                 return status;
             }
             return STATUS_INVALID_HANDLE;
diff --git a/include/winternl.h b/include/winternl.h
index 41bc56d186d..562a35a83a1 100644
--- a/include/winternl.h
+++ b/include/winternl.h
@@ -4612,11 +4612,12 @@ static inline PLIST_ENTRY RemoveTailList(PLIST_ENTRY le)
 
 #ifdef __WINESRC__
 
+typedef NTSTATUS (*unixlib_entry_t)( void *args );
+typedef UINT64 unixlib_handle_t;
+
 /* Wine internal functions */
 extern NTSTATUS CDECL __wine_init_unix_lib( HMODULE module, DWORD reason, const void *ptr_in, void *ptr_out );
-extern NTSTATUS CDECL __wine_unix_call( UINT64 handle, unsigned int code, void *args );
-
-typedef NTSTATUS (*unixlib_entry_t)( void *args );
+extern NTSTATUS CDECL __wine_unix_call( unixlib_handle_t handle, unsigned int code, void *args );
 
 /* The thread information for 16-bit threads */
 /* NtCurrentTeb()->SubSystemTib points to this */