diff --git a/avr-threads/src/avr-thread.c b/avr-threads/src/avr-thread.c
--- a/avr-threads/src/avr-thread.c
+++ b/avr-threads/src/avr-thread.c
@@ -54,10 +54,14 @@
 uint8_t avr_thread_idle_stack[128] __attribute__((weak));
 void avr_thread_idle(void)
 {
-    // If we're idling, no need to try to task switch
-    // because there's no one to task switch to.
-    // Let the isr do the switch.
-    for (;;)
-	;
+    set_sleep_mode(SLEEP_MODE_IDLE);
+    while (1) {
+      sleep_enable();
+
+      sleep_cpu();
+
+      sleep_disable();
+      set_sleep_mode(SLEEP_MODE_IDLE);
+    }
 }
 
@@ -62,5 +66,6 @@
 }
 
+
 void avr_thread_init(void)
 {
     // Initialize idle context.