diff --git a/sys/ztimer/Kconfig b/sys/ztimer/Kconfig
index 63d264dbe5..39d1e81467 100644
--- a/sys/ztimer/Kconfig
+++ b/sys/ztimer/Kconfig
@@ -26,11 +26,13 @@ config MODULE_ZTIMER_PERIPH_RTT
     bool "RTT peripheral"
     depends on HAS_PERIPH_RTT
     select MODULE_PERIPH_RTT
+    default y if !MODULE_ZTIMER_PERIPH_TIMER
 
 config MODULE_ZTIMER_PERIPH_TIMER
     bool "Timer peripheral"
     depends on HAS_PERIPH_TIMER
     select MODULE_PERIPH_TIMER
+    default y
 
 endmenu # Backends
 
diff --git a/tests/pkg_umorse/app.config.test b/tests/pkg_umorse/app.config.test
index 6d4301c763..3ce870d695 100644
--- a/tests/pkg_umorse/app.config.test
+++ b/tests/pkg_umorse/app.config.test
@@ -1,6 +1,5 @@
 CONFIG_MODULE_POSIX_SLEEP=y
 CONFIG_MODULE_ZTIMER=y
-CONFIG_MODULE_ZTIMER_PERIPH_TIMER=y
 CONFIG_MODULE_ZTIMER_USEC=y
 CONFIG_MODULE_ZTIMER_MSEC=y
 CONFIG_PACKAGE_UMORSE=y
diff --git a/tests/posix_sleep/app.config.test b/tests/posix_sleep/app.config.test
index fcf9e41a87..adcda0cec0 100644
--- a/tests/posix_sleep/app.config.test
+++ b/tests/posix_sleep/app.config.test
@@ -1,5 +1,4 @@
 CONFIG_MODULE_POSIX_SLEEP=y
 CONFIG_MODULE_ZTIMER=y
-CONFIG_MODULE_ZTIMER_PERIPH_TIMER=y
 CONFIG_MODULE_ZTIMER_USEC=y
 CONFIG_MODULE_ZTIMER_MSEC=y
diff --git a/tests/ztimer_msg/app.config.test b/tests/ztimer_msg/app.config.test
index 5ab2add9e9..733646e663 100644
--- a/tests/ztimer_msg/app.config.test
+++ b/tests/ztimer_msg/app.config.test
@@ -1,5 +1,4 @@
 # this file enables modules defined in Kconfig. Do not use this file for
 # application configuration. This is only needed during migration.
 CONFIG_MODULE_ZTIMER=y
-CONFIG_MODULE_ZTIMER_PERIPH_TIMER=y
 CONFIG_MODULE_ZTIMER_USEC=y
diff --git a/tests/ztimer_mutex_lock_timeout/app.config.test b/tests/ztimer_mutex_lock_timeout/app.config.test
index 5ab2add9e9..733646e663 100644
--- a/tests/ztimer_mutex_lock_timeout/app.config.test
+++ b/tests/ztimer_mutex_lock_timeout/app.config.test
@@ -1,5 +1,4 @@
 # this file enables modules defined in Kconfig. Do not use this file for
 # application configuration. This is only needed during migration.
 CONFIG_MODULE_ZTIMER=y
-CONFIG_MODULE_ZTIMER_PERIPH_TIMER=y
 CONFIG_MODULE_ZTIMER_USEC=y
diff --git a/tests/ztimer_overhead/app.config.test b/tests/ztimer_overhead/app.config.test
index cddaaa4a48..7819e81c5d 100644
--- a/tests/ztimer_overhead/app.config.test
+++ b/tests/ztimer_overhead/app.config.test
@@ -1,6 +1,5 @@
 # this file enables modules defined in Kconfig. Do not use this file for
 # application configuration. This is only needed during migration.
 CONFIG_MODULE_ZTIMER=y
-CONFIG_MODULE_ZTIMER_PERIPH_TIMER=y
 CONFIG_MODULE_ZTIMER_USEC=y
 CONFIG_MODULE_ZTIMER_OVERHEAD=y
diff --git a/tests/ztimer_periodic/app.config.test b/tests/ztimer_periodic/app.config.test
index c7a9beabc3..a049a205fd 100644
--- a/tests/ztimer_periodic/app.config.test
+++ b/tests/ztimer_periodic/app.config.test
@@ -1,7 +1,6 @@
 # this file enables modules defined in Kconfig. Do not use this file for
 # application configuration. This is only needed during migration.
 CONFIG_MODULE_ZTIMER=y
-CONFIG_MODULE_ZTIMER_PERIPH_TIMER=y
 CONFIG_MODULE_ZTIMER_USEC=y
 CONFIG_MODULE_ZTIMER_MSEC=y
 
diff --git a/tests/ztimer_rmutex_lock_timeout/app.config.test b/tests/ztimer_rmutex_lock_timeout/app.config.test
index df672d7153..0d12371292 100644
--- a/tests/ztimer_rmutex_lock_timeout/app.config.test
+++ b/tests/ztimer_rmutex_lock_timeout/app.config.test
@@ -1,6 +1,5 @@
 # this file enables modules defined in Kconfig. Do not use this file for
 # application configuration. This is only needed during migration.
 CONFIG_MODULE_ZTIMER=y
-CONFIG_MODULE_ZTIMER_PERIPH_TIMER=y
 CONFIG_MODULE_ZTIMER_USEC=y
 CONFIG_MODULE_SHELL=y
diff --git a/tests/ztimer_underflow/app.config.test b/tests/ztimer_underflow/app.config.test
index 5ab2add9e9..733646e663 100644
--- a/tests/ztimer_underflow/app.config.test
+++ b/tests/ztimer_underflow/app.config.test
@@ -1,5 +1,4 @@
 # this file enables modules defined in Kconfig. Do not use this file for
 # application configuration. This is only needed during migration.
 CONFIG_MODULE_ZTIMER=y
-CONFIG_MODULE_ZTIMER_PERIPH_TIMER=y
 CONFIG_MODULE_ZTIMER_USEC=y