diff --git a/VM/src/lbuiltins.cpp b/VM/src/lbuiltins.cpp
index cc6e560a..deaf1407 100644
--- a/VM/src/lbuiltins.cpp
+++ b/VM/src/lbuiltins.cpp
@@ -1018,18 +1018,20 @@ static int luauF_tunpack(lua_State* L, StkId res, TValue* arg0, int nresults, St
 
 static int luauF_vector(lua_State* L, StkId res, TValue* arg0, int nresults, StkId args, int nparams)
 {
-#if LUA_VECTOR_SIZE == 4
-    if (nparams >= 4 && nresults <= 1 && ttisnumber(arg0) && ttisnumber(args) && ttisnumber(args + 1) && ttisnumber(args + 2))
-#else
     if (nparams >= 3 && nresults <= 1 && ttisnumber(arg0) && ttisnumber(args) && ttisnumber(args + 1))
-#endif
     {
         double x = nvalue(arg0);
         double y = nvalue(args);
         double z = nvalue(args + 1);
 
 #if LUA_VECTOR_SIZE == 4
-        double w = nvalue(args + 2);
+        double w = 0.0;
+        if (nparams >= 4)
+        {
+            if (!ttisnumber(args + 2))
+                return -1;
+            w = nvalue(args + 2);
+        }
         setvvalue(res, float(x), float(y), float(z), float(w));
 #else
         setvvalue(res, float(x), float(y), float(z), 0.0f);