diff --git a/cpu/atmega1281/include/cpu_conf.h b/cpu/atmega1281/include/cpu_conf.h
index efacab5ef..ccad511d0 100644
--- a/cpu/atmega1281/include/cpu_conf.h
+++ b/cpu/atmega1281/include/cpu_conf.h
@@ -29,17 +29,22 @@ extern "C" {
  * @name Kernel configuration
  *
  * Since printf seems to get memory allocated by the linker/avr-libc the stack
- * size tested sucessfully even with pretty small stacks.k
+ * size tested sucessfully even with pretty small stacks.
  * @{
  */
 #define THREAD_EXTRA_STACKSIZE_PRINTF    (128)
 
 #ifndef THREAD_STACKSIZE_DEFAULT
-#define THREAD_STACKSIZE_DEFAULT   (256)
+#   define THREAD_STACKSIZE_DEFAULT   (256)
 #endif
 
-#define THREAD_STACKSIZE_IDLE      (128)
-#define ISR_STACKSIZE              (0)
+#ifndef THREAD_STACKSIZE_IDLE
+#   define THREAD_STACKSIZE_IDLE      (128)
+#endif
+
+#ifndef ISR_STACKSIZE
+#   define ISR_STACKSIZE              (0)
+#endif
 /** @} */
 
 #ifdef __cplusplus
diff --git a/cpu/msp430-common/include/cpu_conf.h b/cpu/msp430-common/include/cpu_conf.h
index 0a2f9c117..edd54020b 100644
--- a/cpu/msp430-common/include/cpu_conf.h
+++ b/cpu/msp430-common/include/cpu_conf.h
@@ -17,19 +17,29 @@ extern "C" {
  * @name Kernel configuration
  * @{
  */
-#define THREAD_EXTRA_STACKSIZE_PRINTF    (256)
-#define THREAD_EXTRA_STACKSIZE_PRINTF_FLOAT (THREAD_EXTRA_STACKSIZE_PRINTF)
+#ifndef THREAD_EXTRA_STACKSIZE_PRINTF
+#   define THREAD_EXTRA_STACKSIZE_PRINTF    (256)
+#endif
+
+#ifndef THREAD_EXTRA_STACKSIZE_PRINTF
+#   define THREAD_EXTRA_STACKSIZE_PRINTF_FLOAT (THREAD_EXTRA_STACKSIZE_PRINTF)
+#endif
 
 #ifndef THREAD_STACKSIZE_DEFAULT
-#define THREAD_STACKSIZE_DEFAULT   (256)
+#   define THREAD_STACKSIZE_DEFAULT         (256)
 #endif
 
-#define THREAD_STACKSIZE_IDLE      (96)
-#define ISR_STACKSIZE              (256)
+#ifndef THREAD_STACKSIZE_IDLE
+#   define THREAD_STACKSIZE_IDLE            (96)
+#endif
+
+#ifndef ISR_STACKSIZE
+#   define ISR_STACKSIZE                    (256)
+#endif
 
 #ifndef GNRC_PKTBUF_SIZE
-#define GNRC_PKTBUF_SIZE                (2560)    /* TODO: Make this value
-                                                   * overall MTU dependent */
+/* TODO: Make this value overall MTU dependent */
+#   define GNRC_PKTBUF_SIZE                 (2560)
 #endif
 /** @} */