diff --git a/core/include/sched.h b/core/include/sched.h
index 0328a2bc95..2511e0bb5e 100644
--- a/core/include/sched.h
+++ b/core/include/sched.h
@@ -82,7 +82,6 @@
 
 #include <stddef.h>
 #include "kernel_defines.h"
-#include "bitarithm.h"
 #include "kernel_types.h"
 #include "native_sched.h"
 #include "clist.h"
diff --git a/cpu/nrf52/periph/usbdev.c b/cpu/nrf52/periph/usbdev.c
index 8e0b0a6be9..86e1ababf1 100644
--- a/cpu/nrf52/periph/usbdev.c
+++ b/cpu/nrf52/periph/usbdev.c
@@ -31,6 +31,7 @@
 #include "periph/usbdev.h"
 #include "usb.h"
 #include "usb/descriptor.h"
+#include "bitarithm.h"
 
 #define ENABLE_DEBUG (0)
 #include "debug.h"
diff --git a/cpu/sam0_common/periph/rtt.c b/cpu/sam0_common/periph/rtt.c
index 384ca92fd0..32dbab12e7 100644
--- a/cpu/sam0_common/periph/rtt.c
+++ b/cpu/sam0_common/periph/rtt.c
@@ -32,7 +32,8 @@
  * effects, but simplifies the code. (This bit is always set on SAML21xxxxA)
  */
 #ifndef RTC_MODE0_CTRLA_COUNTSYNC
-#define RTC_MODE0_CTRLA_COUNTSYNC   BIT15
+#define RTC_MODE0_CTRLA_COUNTSYNC_Pos   15
+#define RTC_MODE0_CTRLA_COUNTSYNC       (0x1ul << RTC_MODE0_CTRLA_COUNTSYNC_Pos)
 #endif
 
 static rtt_cb_t _overflow_cb;
diff --git a/sys/frac/frac.c b/sys/frac/frac.c
index 35c69855e6..fe80afff91 100644
--- a/sys/frac/frac.c
+++ b/sys/frac/frac.c
@@ -19,6 +19,7 @@
 #include <stdio.h>
 #include "assert.h"
 #include "frac.h"
+#include "bitarithm.h"
 
 #define ENABLE_DEBUG (0)
 #include "debug.h"