diff --git a/src/apis/http.cpp b/src/apis/http.cpp
index 2794a31f..5148145c 100644
--- a/src/apis/http.cpp
+++ b/src/apis/http.cpp
@@ -1378,8 +1378,8 @@ static int websocket_server_close(lua_State *L) {
     lastCFunction = __func__;
     Computer * comp = get_comp(L);
     websocket_server::Factory * f = *(websocket_server::Factory**)lua_touserdata(L, lua_upvalueindex(1));
-    comp->openWebsocketServers.erase(f->srv->port());
     if (f == NULL) return 0;
+    comp->openWebsocketServers.erase(f->srv->port());
     f->srv->stop();
     delete f->srv;
     *(websocket_server::Factory**)lua_touserdata(L, lua_upvalueindex(1)) = NULL;
@@ -1390,8 +1390,8 @@ static int websocket_server_free(lua_State *L) {
     lastCFunction = __func__;
     Computer * comp = get_comp(L);
     websocket_server::Factory * f = *(websocket_server::Factory**)lua_touserdata(L, 1);
-    comp->openWebsocketServers.erase(f->srv->port());
     if (f == NULL) return 0;
+    comp->openWebsocketServers.erase(f->srv->port());
     f->srv->stop();
     delete f->srv;
     *(websocket_server::Factory**)lua_touserdata(L, 1) = NULL;