diff --git a/cpu/atmega_common/include/cpu_conf.h b/cpu/atmega_common/include/cpu_conf.h
index bd00d7e278..e97dd2fb0d 100644
--- a/cpu/atmega_common/include/cpu_conf.h
+++ b/cpu/atmega_common/include/cpu_conf.h
@@ -49,8 +49,16 @@ extern "C" {
  * to avoid not printing of debug in interrupts
  */
 #ifndef THREAD_STACKSIZE_IDLE
+#ifdef MODULE_XTIMER
+/* xtimer's 64 bit arithmetic doesn't perform well on 8 bit archs. In order to
+ * prevent a stack overflow when an timer triggers while the idle thread is
+ * running, we have to increase the stack size then
+ */
+#define THREAD_STACKSIZE_IDLE      (192)
+#else
 #define THREAD_STACKSIZE_IDLE      (128)
 #endif
+#endif
 /** @} */
 
 /**