diff --git a/cpu/cortexm_common/Kconfig b/cpu/cortexm_common/Kconfig
index 76ffacab2b..b9eb32b938 100644
--- a/cpu/cortexm_common/Kconfig
+++ b/cpu/cortexm_common/Kconfig
@@ -8,6 +8,7 @@ config MODULE_CORTEXM_COMMON
     bool
     default y if CPU_CORE_CORTEX_M
     depends on TEST_KCONFIG
+    imply MODULE_NEWLIB_NANO
     select MODULE_PERIPH
     select MODULE_MALLOC_THREAD_SAFE if TEST_KCONFIG
     help
@@ -141,3 +142,8 @@ config MODULE_MPU_STACK_GUARD
 endmenu # Cortex-M
 
 rsource "periph/Kconfig"
+
+choice LIBC_IMPLEMENTATION
+    default MODULE_NEWLIB
+    default MODULE_PICOLIBC
+endchoice
diff --git a/cpu/cortexm_common/Makefile.features b/cpu/cortexm_common/Makefile.features
index aa667450f6..7992bc8c8b 100644
--- a/cpu/cortexm_common/Makefile.features
+++ b/cpu/cortexm_common/Makefile.features
@@ -39,9 +39,3 @@ else
 endif
 
 FEATURES_PROVIDED += no_idle_thread
-
-# This configuration enables modules that are only available when using Kconfig
-# module modelling
-ifeq (1, $(TEST_KCONFIG))
-  KCONFIG_CPU_CONFIG += $(RIOTCPU)/cortexm_common/cortexm_common.config
-endif
diff --git a/cpu/cortexm_common/cortexm_common.config b/cpu/cortexm_common/cortexm_common.config
deleted file mode 100644
index 37c0e1b7be..0000000000
--- a/cpu/cortexm_common/cortexm_common.config
+++ /dev/null
@@ -1,5 +0,0 @@
-# all cortex MCU's use newlib as libc
-CONFIG_MODULE_NEWLIB=y
-
-# use the nano-specs of Newlib when available
-CONFIG_MODULE_NEWLIB_NANO=y