diff --git a/etc/make/conf.mk b/etc/make/conf.mk
index c7e5b8b..fb358ee 100644
--- a/etc/make/conf.mk
+++ b/etc/make/conf.mk
@@ -74,7 +74,8 @@ OBJS+=$(O)/sys/debug.o \
 	  $(O)/sys/random.o \
 	  $(O)/sys/init.o \
 	  $(O)/sys/vfs/vfs_ops.o \
-	  $(O)/sys/vfs/vfs_access.o
+	  $(O)/sys/vfs/vfs_access.o \
+	  $(O)/sys/time.o
 
 # \
 	  $(O)/sys/vfs/pty.o \
diff --git a/include/sys/amd64/hw/rtc.h b/include/sys/amd64/hw/rtc.h
index 7ccca18..1c6c43e 100644
--- a/include/sys/amd64/hw/rtc.h
+++ b/include/sys/amd64/hw/rtc.h
@@ -1,16 +1,6 @@
 #pragma once
 #include "sys/types.h"
 
-struct rtc_time {
-    uint8_t second;
-    uint8_t minute;
-    uint8_t hour;
-    uint8_t weekday;
-    uint8_t day;
-    uint8_t month;
-    uint16_t year;
-};
-
-void rtc_read(struct rtc_time *time);
+void rtc_read(struct tm *time);
 void rtc_set_century(uint8_t c);
 void rtc_init(void);
diff --git a/include/sys/time.h b/include/sys/time.h
index b85f317..46de5c7 100644
--- a/include/sys/time.h
+++ b/include/sys/time.h
@@ -19,5 +19,12 @@ struct timespec {
 typedef uint64_t time_t;
 
 #if defined(__KERNEL__)
+struct tm;
+
+// Nanoseconds since boot
 extern uint64_t system_time;
+// Seconds since epoch
+extern time_t system_boot_time;
+
+time_t mktime(struct tm *tm);
 #endif
diff --git a/include/sys/types.h b/include/sys/types.h
index 2a2986a..c06286c 100644
--- a/include/sys/types.h
+++ b/include/sys/types.h
@@ -5,6 +5,20 @@
 #define NULL ((void *) 0)
 #endif
 
+#if defined(__KERNEL__)
+struct tm {
+    int tm_sec;
+    int tm_min;
+    int tm_hour;
+    int tm_mday;
+    int tm_mon;
+    int tm_year;
+    int tm_wday;
+    int tm_yday;
+    int tm_isdst;
+};
+#endif
+
 typedef uint64_t uintptr_t;
 typedef int64_t intptr_t;
 
diff --git a/sys/amd64/hw/rtc.c b/sys/amd64/hw/rtc.c
index 0158fe9..1491000 100644
--- a/sys/amd64/hw/rtc.c
+++ b/sys/amd64/hw/rtc.c
@@ -50,16 +50,16 @@ static inline uint8_t cmos_read_time(uint8_t reg, uint8_t reg_b) {
     }
 }
 
-void rtc_read(struct rtc_time *time) {
+void rtc_read(struct tm *time) {
     uint8_t reg_b = cmos_inb(RTC_REGB_STATUS);
 
-    time->second = cmos_read_time(RTC_REG_SECOND, reg_b);
-    time->minute = cmos_read_time(RTC_REG_MINUTE, reg_b);
-    time->hour = cmos_read_time(RTC_REG_HOUR, reg_b);
-    time->weekday = cmos_read_time(RTC_REG_WEEKDAY, reg_b);
-    time->day = cmos_read_time(RTC_REG_DAY, reg_b);
-    time->month = cmos_read_time(RTC_REG_MONTH, reg_b);
-    time->year = cmos_read_time(RTC_REG_YEAR, reg_b) + 100 * rtc_century;
+    time->tm_sec = cmos_read_time(RTC_REG_SECOND, reg_b);
+    time->tm_min = cmos_read_time(RTC_REG_MINUTE, reg_b);
+    time->tm_hour = cmos_read_time(RTC_REG_HOUR, reg_b);
+    //time->tm_wday = cmos_read_time(RTC_REG_WEEKDAY, reg_b);
+    time->tm_mday = cmos_read_time(RTC_REG_DAY, reg_b);
+    time->tm_mon = cmos_read_time(RTC_REG_MONTH, reg_b);
+    time->tm_year = cmos_read_time(RTC_REG_YEAR, reg_b) + 100 * rtc_century;
 }
 
 static uint32_t rtc_irq(void *ctx) {
@@ -94,25 +94,7 @@ void rtc_set_century(uint8_t century) {
 }
 
 void rtc_init(void) {
-    static const char *day_names[] = {
-        "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
-    };
-    static const char *month_names[] = {
-        "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul",
-        "Aug", "Sep", "Oct", "Nov", "Dec"
-    };
-
-    struct rtc_time time;
-
     cmos_inb(RTC_REGC_STATUS);
     irq_add_leg_handler(8, rtc_irq, NULL);
     rtc_enable_irq();
-
-    rtc_read(&time);
-    kdebug("%s %02u %s %04u %02u:%02u:%02u\n",
-            day_names[(time.weekday - 1) % 7],
-            time.day,
-            month_names[(time.month - 1) % 12],
-            time.year,
-            time.hour, time.minute, time.second);
 }
diff --git a/sys/amd64/hw/timer.c b/sys/amd64/hw/timer.c
index 4590ddf..43581c1 100644
--- a/sys/amd64/hw/timer.c
+++ b/sys/amd64/hw/timer.c
@@ -21,7 +21,6 @@
 #define PIT_CMD                     0x43
 
 uint64_t int_timer_ticks = 0;
-uint64_t system_time = 0;
 
 static uint32_t timer_tick(void *arg) {
     switch ((uint64_t) arg) {
diff --git a/sys/amd64/kernel.c b/sys/amd64/kernel.c
index 30433c4..defdef7 100644
--- a/sys/amd64/kernel.c
+++ b/sys/amd64/kernel.c
@@ -28,12 +28,7 @@
 static multiboot_info_t *multiboot_info;
 
 static void amd64_make_random_seed(void) {
-    struct rtc_time t;
-    rtc_read(&t);
-
-    uint64_t s = 137831;
-    s += t.second + t.minute * 60 + t.hour * 3600 + t.day * 86400;
-    random_init(s + system_time);
+    random_init(15267 + system_time);
 }
 
 void kernel_main(struct amd64_loader_data *data) {
@@ -64,6 +59,14 @@ void kernel_main(struct amd64_loader_data *data) {
 
     amd64_apic_init();
     rtc_init();
+    // Setup system time
+    struct tm t;
+    rtc_read(&t);
+    system_boot_time = mktime(&t);
+    kinfo("Boot time: %04u-%02u-%02u %02u:%02u:%02u\n",
+        t.tm_year, t.tm_mon, t.tm_mday,
+        t.tm_hour, t.tm_min, t.tm_sec);
+
     pci_init();
 
     vfs_init();
diff --git a/sys/amd64/sys_sys.c b/sys/amd64/sys_sys.c
index 563f533..28f5292 100644
--- a/sys/amd64/sys_sys.c
+++ b/sys/amd64/sys_sys.c
@@ -62,14 +62,8 @@ int sys_gettimeofday(struct timeval *tv, struct timezone *tz) {
         tz->tz_minuteswest = 0;
     }
 
-    uint64_t secs = system_time / 1000000000ULL;
-
-    struct rtc_time time_rtc;
-    rtc_read(&time_rtc);
-    secs += time_rtc.second + time_rtc.minute * 60 + time_rtc.hour * 3600;
-
+    uint64_t secs = system_time / 1000000000ULL + system_boot_time;
     // System time is in nanos
-    // TODO: use RTC-provided time for full system time
     tv->tv_usec = (system_time / 1000) % 1000000;
     tv->tv_sec = secs;
 
diff --git a/sys/time.c b/sys/time.c
new file mode 100644
index 0000000..6b03d51
--- /dev/null
+++ b/sys/time.c
@@ -0,0 +1,49 @@
+#include "sys/time.h"
+#include "sys/types.h"
+
+#define leap_days_to_1970           477
+
+uint64_t system_time = 0;
+time_t system_boot_time = 0;
+
+static const int days_to_month365[] = {
+    0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
+};
+
+static const int days_to_month366[] = {
+    0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366
+};
+
+static inline int is_leap(int year) {
+    return (year % 4 == 0 && ((year % 100 != 0) || (year % 400 == 0)));
+}
+
+static int tm_check(const struct tm *tm) {
+    return tm->tm_mday < 0 || tm->tm_mday > 31 ||
+           tm->tm_mon < 0 || tm->tm_mon > 12 ||
+           tm->tm_year < 1970 || tm->tm_year > 2500 ||
+           tm->tm_hour < 0 || tm->tm_hour > 23 ||
+           tm->tm_min < 0 || tm->tm_min > 59 ||
+           tm->tm_sec < 0 || tm->tm_sec > 59;
+}
+
+time_t mktime(struct tm *tm) {
+    if (tm_check(tm) != 0) {
+        return 0;
+    }
+
+    // Calculate year day when month starts
+    int month_startd = (is_leap(tm->tm_year) ? days_to_month366 : days_to_month365)[tm->tm_mon - 1];
+
+    // Calculate number of days from epoch to year start
+    int prev_year = tm->tm_year;
+    int days_before = ((prev_year - 1970) * 365) + (prev_year) / 4 - (prev_year) / 100 + (prev_year / 400) - leap_days_to_1970;
+
+    // Add number of seconds in epoch days
+    time_t result = days_before + month_startd + tm->tm_mday - 2;
+    result *= 86400;
+
+    result += tm->tm_hour * 3600 + tm->tm_min * 60 + tm->tm_sec;
+
+    return result;
+}