diff --git a/module/lua/lapi.c b/module/lua/lapi.c
index ed3a0f4cf9..703cf4cc2a 100644
--- a/module/lua/lapi.c
+++ b/module/lua/lapi.c
@@ -444,7 +444,7 @@ LUA_API const void *lua_topointer (lua_State *L, int idx) {
     case LUA_TTABLE: return hvalue(o);
     case LUA_TLCL: return clLvalue(o);
     case LUA_TCCL: return clCvalue(o);
-    case LUA_TLCF: return cast(void *, cast(size_t, fvalue(o)));
+    case LUA_TLCF: return cast(void *, cast(uintptr_t, fvalue(o)));
     case LUA_TTHREAD: return thvalue(o);
     case LUA_TUSERDATA:
     case LUA_TLIGHTUSERDATA: