diff --git a/packages/binding-mqtt/src/mqtt-client.ts b/packages/binding-mqtt/src/mqtt-client.ts
index 2b1f2d15a..bbb9d1cf5 100644
--- a/packages/binding-mqtt/src/mqtt-client.ts
+++ b/packages/binding-mqtt/src/mqtt-client.ts
@@ -40,7 +40,7 @@ export default class MqttClient implements ProtocolClient {
         this.scheme = "mqtt" + (secure ? "s" : "");
     }
 
-    private client: mqtt.MqttClient = undefined;
+    private client?: mqtt.MqttClient;
 
     public subscribeResource(
         form: MqttForm,
@@ -166,8 +166,13 @@ export default class MqttClient implements ProtocolClient {
         const security: TD.SecurityScheme = metadata[0];
 
         if (security.scheme === "basic") {
-            this.config.username = credentials.username;
-            this.config.password = credentials.password;
+            if (credentials === undefined) {
+                // FIXME: This error message should be reworded and adapt to logging convention
+                throw new Error("binding-mqtt: security wants to be basic but you have provided no credentials");
+            } else {
+                this.config.username = credentials.username;
+                this.config.password = credentials.password;
+            }
         }
         return true;
     }
diff --git a/packages/binding-mqtt/src/mqtt.ts b/packages/binding-mqtt/src/mqtt.ts
index b5e5418a4..459557c34 100644
--- a/packages/binding-mqtt/src/mqtt.ts
+++ b/packages/binding-mqtt/src/mqtt.ts
@@ -47,7 +47,7 @@ export class MqttForm extends Form {
 }
 
 export interface MqttClientConfig {
-    // username & password are redundated here (also find them in MqttClientSecurityParameters)
+    // username & password are redundant here (also find them in MqttClientSecurityParameters)
     // because MqttClient.setSecurity() method can inject authentication credentials into this interface
     // which will be then passed to mqtt.connect() once for all
     username?: string;
diff --git a/packages/binding-mqtt/tsconfig.json b/packages/binding-mqtt/tsconfig.json
index e9fa7c062..df9cd1d90 100644
--- a/packages/binding-mqtt/tsconfig.json
+++ b/packages/binding-mqtt/tsconfig.json
@@ -2,7 +2,8 @@
     "extends": "../../tsconfig.json",
     "compilerOptions": {
         "outDir": "dist",
-        "rootDir": "src"
+        "rootDir": "src",
+        "strict": true
     },
     "include": ["src/**/*"],
     "references": [{ "path": "../td-tools" }, { "path": "../core" }]