diff --git a/tests/m48t59-test.c b/tests/m48t59-test.c
index 5179681ca5a842972fa3c67faea600f3f080c0aa..d79f55472dda724c3a099d1b7f794beff4a25032 100644
--- a/tests/m48t59-test.c
+++ b/tests/m48t59-test.c
@@ -233,6 +233,11 @@ static void fuzz_registers(void)
         reg = (uint8_t)g_test_rand_int_range(0, 16);
         val = (uint8_t)g_test_rand_int_range(0, 256);
 
+        if (reg == 7) {
+            /* watchdog setup register, may trigger system reset, skip */
+            continue;
+        }
+
         cmos_write(reg, val);
         cmos_read(reg);
     }
diff --git a/tests/rtc-test.c b/tests/rtc-test.c
index 02edbf5727c208b7b671f3e3c601262f2fd1b4ab..e7123cafbc8f3910e4acae9d68d701ba60f24566 100644
--- a/tests/rtc-test.c
+++ b/tests/rtc-test.c
@@ -201,6 +201,10 @@ static void set_year_20xx(void)
     g_assert_cmpint(cmos_read(RTC_YEAR), ==, 0x11);
     g_assert_cmpint(cmos_read(RTC_CENTURY), ==, 0x20);
 
+    if (sizeof(time_t) == 4) {
+        return;
+    }
+
     /* Set a date in 2080 to ensure there is no year-2038 overflow.  */
     cmos_write(RTC_REG_A, 0x76);
     cmos_write(RTC_YEAR, 0x80);