diff --git a/cpu/samd21/periph/i2c.c b/cpu/samd21/periph/i2c.c
index d06eb37eff..551ca7aa0b 100644
--- a/cpu/samd21/periph/i2c.c
+++ b/cpu/samd21/periph/i2c.c
@@ -12,6 +12,7 @@
  * @file
  * @brief       Low-level I2C driver implementation
  * @author      Baptiste Clenet <baptiste.clenet@xsoen.com>
+ * @author      Thomas Eichinger <thomas.eichinger@fu-berlin.de>
  * @}
  */
 
@@ -19,7 +20,7 @@
 
 #include "cpu.h"
 #include "board.h"
-
+#include "mutex.h"
 #include "periph_conf.h"
 #include "periph/i2c.h"
 #include "instance/instance_sercom3.h"
@@ -41,6 +42,23 @@ static inline void _write(SercomI2cm *dev, char *data, int length);
 static inline void _read(SercomI2cm *dev, char *data, int length);
 static inline void _stop(SercomI2cm *dev);
 
+/**
+ * @brief Array holding one pre-initialized mutex for each I2C device
+ */
+static mutex_t locks[] =  {
+#if I2C_0_EN
+    [I2C_0] = MUTEX_INIT,
+#endif
+#if I2C_1_EN
+    [I2C_1] = MUTEX_INIT,
+#endif
+#if I2C_2_EN
+    [I2C_2] = MUTEX_INIT
+#endif
+#if I2C_3_EN
+    [I2C_3] = MUTEX_INIT
+#endif
+};
 
 int i2c_init_master(i2c_t dev, i2c_speed_t speed)
 {
@@ -191,6 +209,24 @@ int i2c_init_slave(i2c_t dev, uint8_t address)
     return 0;
 }
 
+int i2c_acquire(i2c_t dev)
+{
+    if (dev >= I2C_NUMOF) {
+        return -1;
+    }
+    mutex_lock(&locks[dev]);
+    return 0;
+}
+
+int i2c_release(i2c_t dev)
+{
+    if (dev >= I2C_NUMOF) {
+        return -1;
+    }
+    mutex_unlock(&locks[dev]);
+    return 0;
+}
+
 int i2c_read_byte(i2c_t dev, uint8_t address, char *data)
 {
     return i2c_read_bytes(dev, address, data, 1);