diff --git a/cpu/samd21/cpu.c b/cpu/samd21/cpu.c
index bfb7acaa7db9d..1a17fb8a76442 100644
--- a/cpu/samd21/cpu.c
+++ b/cpu/samd21/cpu.c
@@ -21,32 +21,9 @@
 
 #include "cpu.h"
 #include "periph_conf.h"
+#include "periph_clock_config.h"
 #include "periph/init.h"
 
-#ifndef CLOCK_8MHZ
-#define CLOCK_8MHZ              (8000000UL)
-#endif
-
-#ifndef CLOCK_XOSC32K
-#define CLOCK_XOSC32K           (0)
-#endif
-
-#ifndef XOSC32_RUNSTDBY
-#define XOSC32_RUNSTDBY         (0)
-#endif
-
-#ifndef GEN1_1MHZ
-#define GEN1_1MHZ               (1)
-#endif
-
-#ifndef GEN2_XOSC32
-#define GEN2_XOSC32             (0)
-#endif
-
-#ifndef GEN3_ULP32K
-#define GEN3_ULP32K             (1)
-#endif
-
 #ifndef VDD
 /**
  * @brief   Set system voltage level in mV (determines flash wait states)
diff --git a/cpu/samd21/include/periph_clock_config.h b/cpu/samd21/include/periph_clock_config.h
new file mode 100644
index 0000000000000..6d0bc8c18fd3e
--- /dev/null
+++ b/cpu/samd21/include/periph_clock_config.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2017 Daniel Evans <photonthunder@gmail.com>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup         cpu_samd21
+ * @{
+ *
+ * @file
+ * @brief           CPU specific definitions for default clock configuration
+ *
+ * @author          Daniel Evans <photonthunder@gmail.com>
+ */
+
+#ifndef PERIPH_CLOCK_CONFIG_H
+#define PERIPH_CLOCK_CONFIG_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+    
+    /**
+     * @brief   Default Clock configurations
+     */
+#ifndef CLOCK_8MHZ
+#define CLOCK_8MHZ              (8000000UL)
+#endif
+    
+#ifndef CLOCK_XOSC32K
+#define CLOCK_XOSC32K           (0)
+#endif
+    
+#ifndef XOSC32_RUNSTDBY
+#define XOSC32_RUNSTDBY         (0)
+#endif
+    
+#ifndef GEN1_1MHZ
+#define GEN1_1MHZ               (1)
+#endif
+    
+#ifndef GEN2_XOSC32
+#define GEN2_XOSC32             (0)
+#endif
+    
+#ifndef GEN3_ULP32K
+#define GEN3_ULP32K             (1)
+#endif
+    
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* PERIPH_CLOCK_CONFIG_H */
+/** @} */
diff --git a/cpu/samd21/periph/rtc.c b/cpu/samd21/periph/rtc.c
index 6daa2030f3a1d..eeb5eab37a73c 100644
--- a/cpu/samd21/periph/rtc.c
+++ b/cpu/samd21/periph/rtc.c
@@ -23,6 +23,8 @@
 #include "cpu.h"
 #include "periph/rtc.h"
 #include "periph_conf.h"
+#include "periph_clock_config.h"
+
 
 /* guard file in case no RTC device was specified */
 #if RTC_NUMOF
diff --git a/cpu/samd21/periph/rtt.c b/cpu/samd21/periph/rtt.c
index 8ca5aafbf2636..f69768a146635 100644
--- a/cpu/samd21/periph/rtt.c
+++ b/cpu/samd21/periph/rtt.c
@@ -23,6 +23,7 @@
 #include "cpu.h"
 #include "periph/rtt.h"
 #include "periph_conf.h"
+#include "periph_clock_config.h"
 
 /* guard file in case no RTT device was specified */
 #if RTT_NUMOF
diff --git a/cpu/samd21/periph/timer.c b/cpu/samd21/periph/timer.c
index ea33e35fa4f85..4acffe91af37a 100644
--- a/cpu/samd21/periph/timer.c
+++ b/cpu/samd21/periph/timer.c
@@ -27,6 +27,7 @@
 
 #include "periph/timer.h"
 #include "periph_conf.h"
+#include "periph_clock_config.h"
 
 #define ENABLE_DEBUG    (0)
 #include "debug.h"