diff --git a/config.mk b/config.mk
index 4a8f635..bad2ce3 100644
--- a/config.mk
+++ b/config.mk
@@ -7,8 +7,14 @@ SYSPREFIX = /usr
 ICONSPREFIX = $(SYSPREFIX)/share/icons
 XSESSIONSPREFIX = $(SYSPREFIX)/share/xsessions
 
-INCS =
-LIBS =
+X11INC = /usr/X11R6/include
+X11LIB = /usr/X11R6/lib
+# FreeBSD (uncomment)
+#X11INC = /usr/local/include
+#X11LIB = /usr/local/lib
+
+INCS = -I${X11INC}
+LIBS = -L${X11LIB} -lX11 -lpthread
 
 CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_POSIX_C_SOURCE=200809L -DVERSION=\"$(VERSION)\"
 CFLAGS = -std=c99 -pedantic -Wall -Wextra -Os $(INCS) $(CPPFLAGS)
diff --git a/main.c b/main.c
index b84e168..b0d353b 100644
--- a/main.c
+++ b/main.c
@@ -1,11 +1,21 @@
+#include <pthread.h>
+#include <stdbool.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>
+#include <X11/Xlib.h>
 
-#define WM_STARTUP_TIME_SEC 3
+static bool datetime_running = false;
+static Display *datetime_display = NULL;
+static pthread_t datetime_thread;
+static bool datetime_thread_created = false;
+
+static bool datetime_start();
+static void datetime_stop();
+static void *datetime_run(void *arg);
 
 int main()
 {
@@ -23,10 +33,65 @@ int main()
 		exit(EXIT_FAILURE);
 	}
 
-	for (unsigned int i = 0; i < WM_STARTUP_TIME_SEC; ++i) sleep(1);
+	datetime_start();
 
 	int wm_status;
 	waitpid(wm_pid, &wm_status, 0);
 
+	datetime_stop();
+
 	exit(WEXITSTATUS(wm_status));
 }
+
+bool datetime_start()
+{
+	// TODO: maybe we should assert
+	if (datetime_running) return false;
+	datetime_running = true;
+
+	if ((datetime_display = XOpenDisplay(NULL)) == NULL) {
+		datetime_stop();
+		return false;
+	}
+
+	if (!(datetime_thread_created =
+			pthread_create(&datetime_thread, NULL, datetime_run, NULL) == 0))
+	{
+		datetime_stop();
+		return false;
+	}
+
+	return true;
+}
+
+void datetime_stop()
+{
+	// TODO: maybe we should assert
+	if (!datetime_running) return;
+	datetime_running = false;
+
+	if (datetime_thread_created) pthread_join(datetime_thread, NULL);
+	if (datetime_display) XCloseDisplay(datetime_display);
+}
+
+void *datetime_run(__attribute__((unused)) void *const arg)
+{
+	while (datetime_running) {
+		time_t curr_time;
+		time(&curr_time);
+
+		const struct tm *const curr_tm = localtime(&curr_time);
+
+		char buffer[256];
+		strftime(buffer, sizeof(buffer), "%a, %e %b %Y, %H:%M:%S", curr_tm);
+
+		XStoreName(datetime_display,
+					DefaultRootWindow(datetime_display),
+					buffer);
+		XSync(datetime_display, False);
+
+		sleep(1);
+	}
+
+	return NULL;
+}