diff --git a/core/thread.c b/core/thread.c
index 6e78c12..03ec00d 100644
--- a/core/thread.c
+++ b/core/thread.c
@@ -232,17 +232,18 @@ int threadOnJieffiesTick()
     disable_IRQs(flags);
     list_foreach(currentThread, nextThread, idx)
     {
-        if (nextThread->state == SLEEPING && nextThread->jiffiesSleeping) {
-            nextThread->jiffiesSleeping--;
-            if (!nextThread->jiffiesSleeping) {
+        if (nextThread->state == SLEEPING) {
+            if (nextThread->jiffiesSleeping)
+                nextThread->jiffiesSleeping--;
+            if (!nextThread->jiffiesSleeping)
                 nextThread->state = READY;
-            }
         }
     }
     list_foreach_named(threadWithTimeout, nextThread, idx, timePrev, timeNext)
     {
-        if (nextThread->state == WAITING && nextThread->jiffiesSleeping) {
-            nextThread->jiffiesSleeping--;
+        if (nextThread->state == WAITING) {
+            if (nextThread->jiffiesSleeping)
+                nextThread->jiffiesSleeping--;
             if (!nextThread->jiffiesSleeping) {
                 nextThread->sleepHaveTimeouted = 1;
                 list_delete_named(threadWithTimeout, nextThread, timePrev, timeNext);
@@ -332,8 +333,6 @@ int threadUsleep(unsigned long usec)
     current->state              = SLEEPING;
     current->sleepHaveTimeouted = 0;
     current->jiffiesSleeping    = usecs_to_jiffies(usec);
-    if (!current->jiffiesSleeping) // sleep at least 1 jiffies
-        current->jiffiesSleeping = 1;
     next                        = threadSelectNext();
 
     assert(next != current);