diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6e1d9a9..08b25f1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -52,6 +52,7 @@ add_library(webfused-static STATIC
 	src/webfused/daemon.c
 	src/webfused/config/config.c
 	src/webfused/config/factory.c
+	src/webfused/log/logger.c
 )
 
 add_executable(webfused
@@ -105,6 +106,7 @@ pkg_check_modules(GMOCK gmock)
 
 add_executable(alltests
     test/test_config.cc
+	test/test_log.cc
 )
 
 target_include_directories(alltests PRIVATE
diff --git a/src/webfused/log/log.h b/src/webfused/log/log.h
new file mode 100644
index 0000000..08a3b54
--- /dev/null
+++ b/src/webfused/log/log.h
@@ -0,0 +1,58 @@
+#ifndef WFD_LOG_H
+#define WFD_LOG_H
+
+#ifndef __cplusplus
+#include <stdarg.h>
+#else
+#include <cstdarg>
+#endif
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#ifndef WFD_LOGLEVEL
+#define WFD_LOGLEVEL WFD_LOGLEVEL_ALL
+#endif
+
+#define WFD_LOGLEVEL_FATAL 1
+#define WFD_LOGLEVEL_ERROR 3
+#define WFD_LOGLEVEL_WARN  4
+#define WFD_LOGLEVEL_INFO  5
+#define WFD_LOGLEVEL_DEBUG 7
+#define WFD_LOGLEVEL_ALL   8
+
+#define WFD_FATAL(...) \
+    WFD_LOG(WFD_LOGLEVEL_FATAL, __VA_ARGS__)
+
+#define WFD_ERROR(...) \
+    WFD_LOG(WFD_LOGLEVEL_ERROR, __VA_ARGS__)
+
+#define WFD_WARN(...) \
+    WFD_LOG(WFD_LOGLEVEL_WARN, __VA_ARGS__)
+
+#define WFD_INFO(...) \
+    WFD_LOG(WFD_LOGLEVEL_INFO, __VA_ARGS__)
+
+#define WFD_DEBUG(...) \
+    WFD_LOG(WFD_LOGLEVEL_DEBUG, __VA_ARGS__)
+
+#define WFD_LOG(level, ...) \
+    do { \
+        if (WFD_LOGLEVEL >= (level)) { \
+            wfd_log((level), __VA_ARGS__); \
+        } \
+    } while (0)
+
+extern void
+wfd_log(
+    int level,
+    char const * format,
+    ...);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/src/webfused/log/logger.c b/src/webfused/log/logger.c
new file mode 100644
index 0000000..2c15fbe
--- /dev/null
+++ b/src/webfused/log/logger.c
@@ -0,0 +1,86 @@
+#include "webfused/log/logger.h"
+#include "webfused/log/log.h"
+
+#include <stddef.h>
+
+struct wfd_logger
+{
+    int level;
+    wfd_logger_log_fn * log;
+    wfd_logger_onclose_fn * onclose;
+    void * user_data;
+};
+
+static void wfd_logger_default_log(
+    void * user_data,
+    int level,
+    char const * format,
+    va_list args);
+
+static struct wfd_logger g_wfd_logger =
+{
+    .level = WFD_LOGLEVEL_ALL,
+    .log = &wfd_logger_default_log,
+    .onclose = NULL,
+    .user_data = NULL
+};
+
+void
+wfd_logger_init(
+    int level,
+    wfd_logger_log_fn * log,
+    wfd_logger_onclose_fn * onclose,
+    void * user_data)
+{
+    wfd_logger_close();
+
+    g_wfd_logger.level = level;
+    g_wfd_logger.log = log;
+    g_wfd_logger.onclose = onclose;
+    g_wfd_logger.user_data = user_data;
+}
+
+void
+wfd_logger_close(void)
+{
+    if (NULL != g_wfd_logger.onclose)
+    {
+        g_wfd_logger.onclose(g_wfd_logger.user_data);
+    }
+
+    g_wfd_logger.level = WFD_LOGLEVEL_ALL;
+    g_wfd_logger.log = &wfd_logger_default_log;
+    g_wfd_logger.onclose = NULL;
+    g_wfd_logger.user_data = NULL;
+}
+
+void
+wfd_log(
+    int level,
+    char const * format,
+    ...)
+{
+    if (g_wfd_logger.level >= level)
+    {
+        va_list args;
+        va_start(args, format);
+        g_wfd_logger.log(
+            g_wfd_logger.user_data,
+            level,
+            format,
+            args);
+        va_end(args);
+    }
+}
+
+static void wfd_logger_default_log(
+    void * user_data,
+    int level,
+    char const * format,
+    va_list args)
+{
+    (void) user_data;
+    (void) level;
+    (void) format;
+    (void) args;
+}
diff --git a/src/webfused/log/logger.h b/src/webfused/log/logger.h
new file mode 100644
index 0000000..2944b9c
--- /dev/null
+++ b/src/webfused/log/logger.h
@@ -0,0 +1,40 @@
+#ifndef WFD_LOGGER_H
+#define WFD_LOGGER_H
+
+#ifndef __cplusplus
+#include <stdarg.h>
+#else
+#include <cstdarg>
+#endif
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+typedef void 
+wfd_logger_log_fn(
+    void * user_data,
+    int level,
+    char const * format,
+    va_list args);
+
+typedef void
+wfd_logger_onclose_fn(
+    void * user_data);
+
+extern void
+wfd_logger_init(
+    int level,
+    wfd_logger_log_fn * log,
+    wfd_logger_onclose_fn * onclose,
+    void * user_data);
+
+extern void
+wfd_logger_close(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/test/test_log.cc b/test/test_log.cc
new file mode 100644
index 0000000..57397f0
--- /dev/null
+++ b/test/test_log.cc
@@ -0,0 +1,152 @@
+#include <gtest/gtest.h>
+#include <gmock/gmock.h>
+
+#include "webfused/log/logger.h"
+#include "webfused/log/log.h"
+
+using ::testing::_;
+using ::testing::StrEq;
+
+namespace
+{
+
+class ILogger
+{
+public:
+    virtual ~ILogger() = default;
+    virtual void log(int level, char const * format, va_list args) = 0;
+    virtual void onclose() = 0;
+};
+
+class MockLogger: public ILogger
+{
+public:
+    MOCK_METHOD3(log, void(int level, char const * format, va_list args));
+    MOCK_METHOD0(onclose, void(void));
+
+    void * getUserData() 
+    {
+        ILogger * logger = this;
+        return reinterpret_cast<void*>(logger);
+    }
+};
+
+}
+
+extern "C"
+{
+
+static void MockLogger_log(
+    void * user_data,
+    int level,
+    char const * format,
+    va_list args)
+{
+    ILogger * logger = reinterpret_cast<ILogger*>(user_data);
+    logger->log(level, format, args);
+}
+
+static void MockLogger_onclose(
+    void * user_data)
+{
+    ILogger * logger = reinterpret_cast<ILogger*>(user_data);
+    logger->onclose();
+}
+
+}
+
+TEST(log, fatal)
+{
+    MockLogger logger;
+
+    EXPECT_CALL(logger, log(WFD_LOGLEVEL_FATAL, StrEq("too bad"), _)).Times(1);
+    EXPECT_CALL(logger, onclose()).Times(1);
+
+    wfd_logger_init(WFD_LOGLEVEL_ALL, &MockLogger_log, &MockLogger_onclose, logger.getUserData());
+    WFD_FATAL("too bad");
+    wfd_logger_close();
+}
+
+TEST(log, error)
+{
+    MockLogger logger;
+
+    EXPECT_CALL(logger, log(WFD_LOGLEVEL_ERROR, StrEq("too bad"), _)).Times(1);
+    EXPECT_CALL(logger, onclose()).Times(1);
+
+    wfd_logger_init(WFD_LOGLEVEL_ALL, &MockLogger_log, &MockLogger_onclose, logger.getUserData());
+    WFD_ERROR("too bad");
+    wfd_logger_close();
+}
+
+TEST(log, warn)
+{
+    MockLogger logger;
+
+    EXPECT_CALL(logger, log(WFD_LOGLEVEL_WARN, StrEq("too bad"), _)).Times(1);
+    EXPECT_CALL(logger, onclose()).Times(1);
+
+    wfd_logger_init(WFD_LOGLEVEL_ALL, &MockLogger_log, &MockLogger_onclose, logger.getUserData());
+    WFD_WARN("too bad");
+    wfd_logger_close();
+}
+
+TEST(log, info)
+{
+    MockLogger logger;
+
+    EXPECT_CALL(logger, log(WFD_LOGLEVEL_INFO, StrEq("too bad"), _)).Times(1);
+    EXPECT_CALL(logger, onclose()).Times(1);
+
+    wfd_logger_init(WFD_LOGLEVEL_ALL, &MockLogger_log, &MockLogger_onclose, logger.getUserData());
+    WFD_INFO("too bad");
+    wfd_logger_close();
+}
+
+TEST(log, debug)
+{
+    MockLogger logger;
+
+    EXPECT_CALL(logger, log(WFD_LOGLEVEL_DEBUG, StrEq("too bad"), _)).Times(1);
+    EXPECT_CALL(logger, onclose()).Times(1);
+
+    wfd_logger_init(WFD_LOGLEVEL_ALL, &MockLogger_log, &MockLogger_onclose, logger.getUserData());
+    WFD_DEBUG("too bad");
+    wfd_logger_close();
+}
+
+TEST(log, respect_loglevel)
+{
+    MockLogger logger;
+
+    EXPECT_CALL(logger, log(_, _, _)).Times(0);
+    EXPECT_CALL(logger, onclose()).Times(1);
+
+    wfd_logger_init(WFD_LOGLEVEL_WARN, &MockLogger_log, &MockLogger_onclose, logger.getUserData());
+    WFD_DEBUG("too bad");
+    wfd_logger_close();
+}
+
+TEST(log, log_same_loglevel)
+{
+    MockLogger logger;
+
+    EXPECT_CALL(logger, log(WFD_LOGLEVEL_WARN, StrEq("too bad"), _)).Times(1);
+    EXPECT_CALL(logger, onclose()).Times(1);
+
+    wfd_logger_init(WFD_LOGLEVEL_WARN, &MockLogger_log, &MockLogger_onclose, logger.getUserData());
+    WFD_WARN("too bad");
+    wfd_logger_close();
+}
+
+TEST(log, omit_onclose_if_nullptr)
+{
+    MockLogger logger;
+
+    EXPECT_CALL(logger, log(WFD_LOGLEVEL_WARN, StrEq("too bad"), _)).Times(1);
+    EXPECT_CALL(logger, onclose()).Times(0);
+
+    wfd_logger_init(WFD_LOGLEVEL_WARN, &MockLogger_log, nullptr, logger.getUserData());
+    WFD_WARN("too bad");
+    wfd_logger_close();
+}