diff --git a/src/WebApi_mqtt.cpp b/src/WebApi_mqtt.cpp
index 08bc913..92eb789 100644
--- a/src/WebApi_mqtt.cpp
+++ b/src/WebApi_mqtt.cpp
@@ -141,6 +141,13 @@ void WebApiMqttClass::onMqttAdminPost(AsyncWebServerRequest* request)
             return;
         }
 
+        if (root[F("mqtt_topic")].as<String>().indexOf(' ') != -1) {
+            retMsg[F("message")] = F("Topic must not contain space characters!");
+            response->setLength();
+            request->send(response);
+            return;
+        }
+
         if (root[F("mqtt_port")].as<uint>() == 0 || root[F("mqtt_port")].as<uint>() > 65535) {
             retMsg[F("message")] = F("Port must be a number between 1 and 65535!");
             response->setLength();
@@ -155,6 +162,13 @@ void WebApiMqttClass::onMqttAdminPost(AsyncWebServerRequest* request)
             return;
         }
 
+        if (root[F("mqtt_lwt_topic")].as<String>().indexOf(' ') != -1) {
+            retMsg[F("message")] = F("LWT topic must not contain space characters!");
+            response->setLength();
+            request->send(response);
+            return;
+        }
+
         if (root[F("mqtt_lwt_online")].as<String>().length() > MQTT_MAX_LWTVALUE_STRLEN) {
             retMsg[F("message")] = F("LWT online value must not longer then " STR(MQTT_MAX_LWTVALUE_STRLEN) " characters!");
             response->setLength();
@@ -183,6 +197,13 @@ void WebApiMqttClass::onMqttAdminPost(AsyncWebServerRequest* request)
                 request->send(response);
                 return;
             }
+
+            if (root[F("mqtt_hass_topic")].as<String>().indexOf(' ') != -1) {
+                retMsg[F("message")] = F("Hass topic must not contain space characters!");
+                response->setLength();
+                request->send(response);
+                return;
+            }
         }
     }