diff --git a/test/fake_adapter_server.cc b/test/fake_adapter_server.cc
index 2656557..72a1831 100644
--- a/test/fake_adapter_server.cc
+++ b/test/fake_adapter_server.cc
@@ -77,7 +77,7 @@ namespace webfuse_test
 class FakeAdapterServer::Private: public IServer
 {
 public:
-    Private(int port)
+    explicit Private(int port)
     : client_wsi(nullptr)
     , message_received(false)
     {
diff --git a/test/fake_adapter_server.hpp b/test/fake_adapter_server.hpp
index 215c9e0..9cc51f0 100644
--- a/test/fake_adapter_server.hpp
+++ b/test/fake_adapter_server.hpp
@@ -11,7 +11,7 @@ class FakeAdapterServer
     FakeAdapterServer(FakeAdapterServer const &) = delete;
     FakeAdapterServer & operator=(FakeAdapterServer const &) = delete;
 public:
-    FakeAdapterServer(int port);
+    explicit FakeAdapterServer(int port);
     ~FakeAdapterServer();
     void waitForConnection();
 private:
diff --git a/test/timeout_watcher.hpp b/test/timeout_watcher.hpp
index 445fb30..278d25f 100644
--- a/test/timeout_watcher.hpp
+++ b/test/timeout_watcher.hpp
@@ -11,7 +11,7 @@ class TimeoutWatcher final
     TimeoutWatcher(TimeoutWatcher const & other) = delete;
     TimeoutWatcher& operator=(TimeoutWatcher const & other) = delete;
 public:
-    TimeoutWatcher(std::chrono::milliseconds timeout);
+    explicit TimeoutWatcher(std::chrono::milliseconds timeout);
     ~TimeoutWatcher();
     bool isTimeout();
     void check();