diff --git a/tests/posix_sleep/Makefile b/tests/posix_sleep/Makefile
index 4c534b1372..2d5f6f5dda 100644
--- a/tests/posix_sleep/Makefile
+++ b/tests/posix_sleep/Makefile
@@ -2,12 +2,4 @@ include ../Makefile.tests_common
 
 USEMODULE += posix_sleep
 
-# These CPU families have a non configurable RTT of 1Hz, not enough for
-# ztimer_msec to run on periph_rtt
-ifeq (,$(filter efm32 kinetis,$(CPU)))
-  # Pull-in periph-rtt on boards that provide this feature to switch to
-  # the RTT backend of ztimer
-  FEATURES_OPTIONAL += periph_rtt
-endif
-
 include $(RIOTBASE)/Makefile.include