diff --git a/src/async.c b/src/async.c
index 5c2f190a..061e9f2c 100644
--- a/src/async.c
+++ b/src/async.c
@@ -54,14 +54,16 @@ static luv_async_send_t* luv_async_pop(luv_async_arg_t* asarg) {
 
 static luv_async_send_t* luv_async_push(luv_async_arg_t* asarg) {
   luv_async_send_t* sendarg = (luv_async_send_t*)malloc(sizeof(luv_async_send_t));
-  memset(sendarg, 0, sizeof(luv_async_send_t));
-  asarg->count++;
-  if (asarg->last != NULL) {
-    asarg->last->next = sendarg;
-  }
-  asarg->last = sendarg;
-  if (asarg->first == NULL) {
-    asarg->first = sendarg;
+  if (sendarg != NULL) {
+    memset(sendarg, 0, sizeof(luv_async_send_t));
+    asarg->count++;
+    if (asarg->last != NULL) {
+      asarg->last->next = sendarg;
+    }
+    asarg->last = sendarg;
+    if (asarg->first == NULL) {
+      asarg->first = sendarg;
+    }
   }
   return sendarg;
 }
@@ -154,25 +156,33 @@ static int luv_async_send(lua_State* L) {
   uv_async_t* handle = luv_check_async(L, 1);
   luv_async_arg_t* asarg = luv_get_async_arg_from_handle(handle);
   uv_mutex_t *argmutex = &asarg->mutex;
-  luv_thread_arg_t* args;
-  int n;
+  luv_thread_arg_t targcpy;
+  ret = luv_thread_arg_set(L, &targcpy, 2, lua_gettop(L), LUVF_THREAD_MODE_ASYNC|LUVF_THREAD_SIDE_CHILD);
+  if (ret < 0) {
+    luv_thread_arg_free(&targcpy);
+    return luv_thread_arg_error(L);
+  }
   uv_mutex_lock(argmutex);
   if (luv_is_async_queue(asarg)) {
-    if (asarg->count >= asarg->max) {
+    luv_async_send_t* sendarg = NULL;
+    ret = UV_ENOSPC;
+    if (asarg->count < asarg->max) {
+      sendarg = luv_async_push(asarg);
+      if (sendarg == NULL) {
+        ret = UV_ENOMEM;
+      }
+    }
+    if (sendarg == NULL) {
       uv_mutex_unlock(argmutex);
-      return luv_error(L, UV_ENOSPC);
+      luv_thread_arg_free(&targcpy);
+      return luv_error(L, ret);
     }
-    luv_async_send_t* sendarg = luv_async_push(asarg);
-    args = &sendarg->targ;
+    sendarg->targ = targcpy;
   } else {
     luv_thread_arg_free(&asarg->targ); // in case of a pending send
-    args = &asarg->targ;
+    asarg->targ = targcpy;
   }
-  n = luv_thread_arg_set(L, args, 2, lua_gettop(L), LUVF_THREAD_MODE_ASYNC|LUVF_THREAD_SIDE_CHILD);
   uv_mutex_unlock(argmutex);
-  if (n < 0) {
-    return luv_thread_arg_error(L);
-  }
   ret = uv_async_send(handle);
   return luv_result(L, ret);
 }
diff --git a/src/thread.c b/src/thread.c
index 7e752eb6..d8021d92 100644
--- a/src/thread.c
+++ b/src/thread.c
@@ -62,6 +62,13 @@ static const char* luv_getmtname(lua_State *L, int idx) {
   return name;
 }
 
+static int luv_thread_arg_set_error(lua_State* L, luv_thread_arg_t* args, int type, int index) {
+  args->argc = index;
+  lua_pushinteger(L, type);
+  lua_pushinteger(L, index + 1);
+  return -1;
+}
+
 static int luv_thread_arg_set(lua_State* L, luv_thread_arg_t* args, int idx, int top, int flags) {
   int i;
   int side = LUVF_THREAD_SIDE(flags);
@@ -72,7 +79,8 @@ static int luv_thread_arg_set(lua_State* L, luv_thread_arg_t* args, int idx, int
   args->flags = flags;
   while (i <= top && i < LUV_THREAD_MAXNUM_ARG + idx)
   {
-    luv_val_t *arg = args->argv + (i - idx);
+    int ii = i - idx;
+    luv_val_t *arg = args->argv + ii;
     arg->type = lua_type(L, i);
     arg->ref[0] = arg->ref[1] = LUA_NOREF;
     switch (arg->type)
@@ -95,6 +103,9 @@ static int luv_thread_arg_set(lua_State* L, luv_thread_arg_t* args, int idx, int
         size_t l = 0;
         const char* p = lua_tolstring(L, i, &l);
         void* b = malloc(l + 1);
+        if (b == NULL) {
+          return luv_thread_arg_set_error(L, args, LUA_TNONE, ii);
+        }
         arg->val.str.base = memcpy((void*)b, p, l + 1);
         arg->val.str.len = l;
       } else {
@@ -111,11 +122,17 @@ static int luv_thread_arg_set(lua_State* L, luv_thread_arg_t* args, int idx, int
         if (async) {
           if (l > 0) {
             void* b = malloc(l);
+            if (b == NULL) {
+              return luv_thread_arg_set_error(L, args, LUA_TNONE, ii);
+            }
             p = (const void*)memcpy(b, p, l);
           }
           if (mtname != NULL) {
             size_t ml = strlen(mtname) + 1;
             char* b = malloc(ml);
+            if (b == NULL) {
+              return luv_thread_arg_set_error(L, args, LUA_TNONE, ii);
+            }
             mtname = (const void*)memcpy(b, mtname, ml);
           }
         } else {
@@ -128,10 +145,7 @@ static int luv_thread_arg_set(lua_State* L, luv_thread_arg_t* args, int idx, int
       }
       break;
     default:
-      args->argc = i - idx;
-      lua_pushinteger(L, arg->type);
-      lua_pushinteger(L, i - idx + 1);
-      return -1;
+      return luv_thread_arg_set_error(L, args, arg->type, ii);
     }
     i++;
   }
@@ -251,6 +265,9 @@ static int luv_thread_arg_error(lua_State *L) {
   int type = lua_tointeger(L, -2);
   int pos = lua_tointeger(L, -1);
   lua_pop(L, 2);
+  if (type == LUA_TNONE) {
+    return luaL_error(L, "Error: thread arg failure at %d", pos);
+  }
   return luaL_error(L, "Error: thread arg not support type '%s' at %d",
     lua_typename(L, type), pos);
 }
diff --git a/tests/test-async.lua b/tests/test-async.lua
index 23c44d9c..d057ea53 100644
--- a/tests/test-async.lua
+++ b/tests/test-async.lua
@@ -28,7 +28,7 @@ return require('lib/tap')(function (test)
     end))
     uv.new_thread(function(asy)
       assert(type(asy)=='userdata')
-      assert(asy:send('not ok')==0) -- will be ignored but its ok
+      assert(asy:send('not ok')==0) -- will be ignored but it's ok
       assert(asy:send('ok')==0)
       require('luv').sleep(10)
     end, async):join()
@@ -62,8 +62,9 @@ return require('lib/tap')(function (test)
       assert(v=='ok')
       async:close()
     end))
-    assert(async:send('not ok')==0) -- will be ignored but its ok
+    assert(async:send('not ok')==0) -- will be ignored but it's ok
     assert(async:send('ok')==0)
+    assert(pcall(uv.async_send, 'not ok', function() end)==false) -- will fail
     uv.run()
   end)