diff --git a/tests/periph/timer_periodic/Makefile b/tests/periph/timer_periodic/Makefile
index c894723314..47756540f1 100644
--- a/tests/periph/timer_periodic/Makefile
+++ b/tests/periph/timer_periodic/Makefile
@@ -4,4 +4,9 @@ FEATURES_REQUIRED = periph_timer_periodic
 
 USEMODULE += fmt
 
+# Interactive sync improves accuracy of timestamping the output
+# and is also needed on native for the automatic test to
+# pass. Hence, we just depend on it here.
+USEMODULE += test_utils_interactive_sync
+
 include $(RIOTBASE)/Makefile.include
diff --git a/tests/sys/posix_sleep/Makefile b/tests/sys/posix_sleep/Makefile
index 5dcb9ed74c..8967a1acd4 100644
--- a/tests/sys/posix_sleep/Makefile
+++ b/tests/sys/posix_sleep/Makefile
@@ -2,6 +2,11 @@ include ../Makefile.sys_common
 
 USEMODULE += posix_sleep
 
+# Interactive sync improves accuracy of timestamping the output
+# and is also needed on native for the automatic test to
+# pass. Hence, we just depend on it here.
+USEMODULE += test_utils_interactive_sync
+
 # microbit qemu failing currently
 TEST_ON_CI_BLACKLIST += microbit