diff --git a/luprex/cpp/core/world-core.cpp b/luprex/cpp/core/world-core.cpp
index 93e4d2d2..308820b7 100644
--- a/luprex/cpp/core/world-core.cpp
+++ b/luprex/cpp/core/world-core.cpp
@@ -769,6 +769,41 @@ void World::invoke_choose(int64_t actor_id, int64_t place_id, std::string_view d
     assert(stack_is_clear());
 }
 
+// Read a SimpleDynamic value from the streambuffer and push
+// it onto the lua stack.
+void push_simple_dynamic(lua_State *L, StreamBuffer *sb) {
+    SimpleDynamicTag type = sb->read_simple_dynamic_tag();
+    switch (type) {
+        case SimpleDynamicTag::NUMBER: {
+            lua_pushnumber(L, sb->read_double());
+            break;
+        }
+        case SimpleDynamicTag::BOOLEAN: {
+            lua_pushboolean(L, sb->read_bool() ? 1:0);
+            break;
+        }
+        case SimpleDynamicTag::STRING: {
+            std::string_view s = sb->read_string_view();
+            lua_pushlstring(L, s.data(), s.size());
+            break;
+        }
+        case SimpleDynamicTag::VECTOR: {
+            double x = sb->read_double();
+            double y = sb->read_double();
+            double z = sb->read_double();
+            lua_newtable(L);
+            lua_pushnumber(L, x);
+            lua_rawseti(L, -2, 1);
+            lua_pushnumber(L, y);
+            lua_rawseti(L, -2, 2);
+            lua_pushnumber(L, z);
+            lua_rawseti(L, -2, 3);
+            break;
+        }
+        default: throw StreamCorruption();
+    }
+}
+
 void World::invoke_engio(int64_t actor_id, int64_t place_id, std::string_view datapack) {
     assert(stack_is_clear());
 
@@ -820,7 +855,7 @@ void World::invoke_engio(int64_t actor_id, int64_t place_id, std::string_view da
         if (!LS.isfunction(func)) {
             return;
         }
-
+        
         // Create a new thread, push func, actor, place.
         int nargs = 3;
         lua_State *CO = LS.newthread(thread);
@@ -831,23 +866,7 @@ void World::invoke_engio(int64_t actor_id, int64_t place_id, std::string_view da
         // Push any additional args from the datapack.
         try {
             while (!datasb.empty()) {
-                SimpleDynamicTag type = datasb.read_simple_dynamic_tag();
-                switch (type) {
-                    case SimpleDynamicTag::NUMBER: {
-                        lua_pushnumber(L, datasb.read_double());
-                        break;
-                    }
-                    case SimpleDynamicTag::BOOLEAN: {
-                        lua_pushboolean(L, datasb.read_bool() ? 1:0);
-                        break;
-                    }
-                    case SimpleDynamicTag::STRING: {
-                        std::string_view s = datasb.read_string_view();
-                        lua_pushlstring(L, s.data(), s.size());
-                        break;
-                    }
-                    default: return;
-                }
+                push_simple_dynamic(L, &datasb);
                 nargs++;
             }
         } catch (const StreamException &exc) {
diff --git a/luprex/lua/login.lua b/luprex/lua/login.lua
index 08197eae..5e5631c9 100644
--- a/luprex/lua/login.lua
+++ b/luprex/lua/login.lua
@@ -53,5 +53,8 @@ function mkt()
 
 makeclass("engio")
 function engio.myfunction(actor, place, a, b, c)
-    print("Myfunction actor=", actor," place=", place, " a=", a, " b=", b, " c=", c)
+    print("Myfunction actor=", actor," place=", place)
+    pprint("A:", a)
+    pprint("B:", b)
+    pprint("C:", c)
     end