diff --git a/tests/classbind-tests/classbind-tests.ino b/tests/classbind-tests/classbind-tests.ino
index bd00c2d..13de492 100644
--- a/tests/classbind-tests/classbind-tests.ino
+++ b/tests/classbind-tests/classbind-tests.ino
@@ -17,7 +17,7 @@ class TestReceiver : public MqttClassBinder<TestReceiver>
   public:
     TestReceiver(const char* name) : MqttClassBinder(), name_(name) {}
 
-    void onPublish(const MqttClient* /* source */, const Topic& topic, const char* payload, size_t /* length */)
+    void onPublish(const MqttClient* /* source */, const Topic& topic, const char* /* payload */, size_t /* length */)
     {
       (void) topic;
       // Serial << "--> routed message received by " << name_ << ':' << topic.c_str() << " = " << payload << endl;
diff --git a/tests/local-tests/local-tests.ino b/tests/local-tests/local-tests.ino
index 6e5139d..f102055 100644
--- a/tests/local-tests/local-tests.ino
+++ b/tests/local-tests/local-tests.ino
@@ -12,8 +12,6 @@
   * Also, this will allow to mock and thus run Action on github
   **/
 
-using namespace std;
-
 MqttBroker broker(1883);
 
 std::map<TinyString, std::map<Topic, int>>  published;    // map[client_id] => map[topic] = count
diff --git a/tests/nowifi-tests/nowifi-tests.ino b/tests/nowifi-tests/nowifi-tests.ino
index bfd2084..813d2ea 100644
--- a/tests/nowifi-tests/nowifi-tests.ino
+++ b/tests/nowifi-tests/nowifi-tests.ino
@@ -11,8 +11,6 @@
   * Checks with a local broker. Clients must connect to the local broker
   **/
 
-using namespace std;
-
 MqttBroker broker(1883);
 
 std::map<TinyString, std::map<Topic, int>>  published;    // map[client_id] => map[topic] = count
diff --git a/tests/string-indexer-tests/string-indexer-tests.ino b/tests/string-indexer-tests/string-indexer-tests.ino
index 7ae54ec..b1f856b 100644
--- a/tests/string-indexer-tests/string-indexer-tests.ino
+++ b/tests/string-indexer-tests/string-indexer-tests.ino
@@ -9,8 +9,6 @@
   *
   **/
 
-using namespace std;
-
 test(indexer_empty)
 {
   assertEqual(StringIndexer::count(), 0);
diff --git a/tests/topic-tests/topic-tests.ino b/tests/topic-tests/topic-tests.ino
index 8b3179b..6090d9a 100644
--- a/tests/topic-tests/topic-tests.ino
+++ b/tests/topic-tests/topic-tests.ino
@@ -5,26 +5,22 @@
 #include <map>
 #include <iostream>
 
-#define endl "\n"
-
 /**
   * TinyMqtt / StringIndexer unit tests.
   *
   **/
 
-using namespace std;
-
 bool testTopicMatch(const char* a, const char* b, bool expected)
 {
   Topic ta(a);
   Topic tb(b);
   bool match(ta.matches(tb));
-  cout << "  " << ta.c_str() << ' ';
+  std::cout << "  " << ta.c_str() << ' ';
   if (match != expected)
-    cout << (expected ? " should match " : " should not match ");
+    std::cout << (expected ? " should match " : " should not match ");
   else
-    cout << (expected ? " matches " : " unmatches ");
-  cout << tb.c_str() << endl;
+    std::cout << (expected ? " matches " : " unmatches ");
+  std::cout << tb.c_str() << std::endl;
   return expected == match;
 }