diff --git a/system-test/auth_change_user_loop.cpp b/system-test/auth_change_user_loop.cpp
index 7c1de4288..f6bdbd442 100644
--- a/system-test/auth_change_user_loop.cpp
+++ b/system-test/auth_change_user_loop.cpp
@@ -118,7 +118,7 @@ int main(int argc, char* argv[])
                       Test->maxscales->password,
                       NULL);
 
-    Test->tprintf("Dropping user", Test->maxscales->user_name);
+    Test->tprintf("Dropping user");
     Test->try_query(Test->maxscales->conn_rwsplit[0], (char*) "DROP USER user@'%%';");
 
     Test->maxscales->verbose = true;
diff --git a/system-test/long_test.cpp b/system-test/long_test.cpp
index 0a8153633..e20e73f22 100644
--- a/system-test/long_test.cpp
+++ b/system-test/long_test.cpp
@@ -122,7 +122,7 @@ int main(int argc, char *argv[])
         {
             data[j][i].sql = (char*) malloc((i +1) * 32 * 14 + 32);
             create_insert_string(data[j][i].sql, (i + 1) * 32, i);
-            Test->tprintf("sqL %d: %d\n", i, strlen(data[j][i].sql));
+            Test->tprintf("sqL %d: %zu\n", i, strlen(data[j][i].sql));
             data[j][i].exit_flag = false;
             data[j][i].id = i;
             pthread_create(&thread_id[j][i], NULL, thread[j], &data[j][i]);
diff --git a/system-test/maxtest/include/maxtest/testconnections.hh b/system-test/maxtest/include/maxtest/testconnections.hh
index 52a8edc6d..06b59cfce 100644
--- a/system-test/maxtest/include/maxtest/testconnections.hh
+++ b/system-test/maxtest/include/maxtest/testconnections.hh
@@ -357,7 +357,7 @@ public:
     /**
      * @brief printf with automatic timestamps
      */
-    void tprintf(const char* format, ...);
+    void tprintf(const char* format, ...) mxb_attribute((format(printf, 2, 3)));
 
     /**
      * @brief injects a message into maxscale.log
diff --git a/system-test/maxtest/src/big_load.cc b/system-test/maxtest/src/big_load.cc
index 27fe0d734..ab0f04af1 100644
--- a/system-test/maxtest/src/big_load.cc
+++ b/system-test/maxtest/src/big_load.cc
@@ -102,7 +102,7 @@ void load(long int* new_inserts,
         Test->tprintf("COM_INSERT and COM_SELECT after executing test\n");
         get_global_status_allnodes(&new_selects[0], &new_inserts[0], nodes, 0);
         print_delta(&new_selects[0], &new_inserts[0], &selects[0], &inserts[0], nodes->N);
-        Test->tprintf("First group of threads did %d queries, second - %d \n", data.i1, data.i2);
+        Test->tprintf("First group of threads did %ld queries, second - %ld \n", data.i1, data.i2);
     }
     nodes->close_connections();
     *i1 = data.i1;
diff --git a/system-test/maxtest/src/blob_test.cc b/system-test/maxtest/src/blob_test.cc
index e4c5188af..70534b9bb 100644
--- a/system-test/maxtest/src/blob_test.cc
+++ b/system-test/maxtest/src/blob_test.cc
@@ -55,7 +55,7 @@ int test_longblob(TestConnections* Test,
 
 
 
-        Test->tprintf("Sending data in %d bytes chunks, total size is %d\n",
+        Test->tprintf("Sending data in %lu bytes chunks, total size is %lu\n",
                       size * sizeof(unsigned long),
                       (size * sizeof(unsigned long)) * chunks);
         for (i = 0; i < chunks; i++)
diff --git a/system-test/maxtest/src/testconnections.cc b/system-test/maxtest/src/testconnections.cc
index f96004103..100f07a28 100644
--- a/system-test/maxtest/src/testconnections.cc
+++ b/system-test/maxtest/src/testconnections.cc
@@ -689,7 +689,7 @@ void TestConnections::read_mdbci_info()
     }
     if (verbose)
     {
-        tprintf(m_network_config.c_str());
+        tprintf("%s", m_network_config.c_str());
     }
 }
 
diff --git a/system-test/mxs1713_lots_of_databases.cpp b/system-test/mxs1713_lots_of_databases.cpp
index 2f34ba327..83cbeb168 100644
--- a/system-test/mxs1713_lots_of_databases.cpp
+++ b/system-test/mxs1713_lots_of_databases.cpp
@@ -28,7 +28,7 @@ int main(int argc, char** argv)
     test.repl->sync_slaves();
     test.tprintf("Done!");
 
-    test.tprintf("Opening a connection with each database as the default database...", db_list.size());
+    test.tprintf("Opening a connection with each database as the default database...");
     std::set<std::string> errors;
     int i = 0;
 
diff --git a/system-test/mxs1926_killed_server.cpp b/system-test/mxs1926_killed_server.cpp
index 07e1a709b..22c81a476 100644
--- a/system-test/mxs1926_killed_server.cpp
+++ b/system-test/mxs1926_killed_server.cpp
@@ -55,7 +55,7 @@ void tune_rowcount(TestConnections& test)
 
         int orig = ROWCOUNT;
         ROWCOUNT = orig / dur.count() * 10000;
-        test.tprintf("Loading %d rows took %d ms, setting row count to %d",
+        test.tprintf("Loading %d rows took %ld ms, setting row count to %d",
                      orig,
                      dur.count(),
                      ROWCOUNT.load());
diff --git a/system-test/mxs1929_start_from_scratch.cpp b/system-test/mxs1929_start_from_scratch.cpp
index 5c927454c..4ca6be8bb 100644
--- a/system-test/mxs1929_start_from_scratch.cpp
+++ b/system-test/mxs1929_start_from_scratch.cpp
@@ -120,7 +120,7 @@ int main(int argc, char** argv)
 
     auto end = std::chrono::steady_clock::now();
 
-    test.tprintf("A total of %d connections were created over %d seconds",
+    test.tprintf("A total of %d connections were created over %ld seconds",
                  conns.load(),
                  std::chrono::duration_cast<std::chrono::seconds>(end - start).count());
 
diff --git a/system-test/mxs812_1.cpp b/system-test/mxs812_1.cpp
index 329bcdda9..b741aef3d 100644
--- a/system-test/mxs812_1.cpp
+++ b/system-test/mxs812_1.cpp
@@ -31,7 +31,7 @@ void run_test(TestConnections& test, size_t size, int chunks)
                     mysql_stmt_error(stmt));
 
     std::string data(size, '.');
-    test.tprintf("Sending %d x %d bytes of data", size, chunks);
+    test.tprintf("Sending %zu x %d bytes of data", size, chunks);
 
     for (int i = 0; i < chunks; i++)
     {