diff --git a/src/threads/synch.c b/src/threads/synch.c
index 3fe957c..f8e6dd3 100644
--- a/src/threads/synch.c
+++ b/src/threads/synch.c
@@ -252,26 +252,17 @@ lock_acquire (struct lock *lock)
 
   struct thread *t = thread_current ();
 
-  if(!thread_mlfqs)
-  {
-
-      enum intr_level old_level = intr_disable ();
-
-      if (lock->holder != NULL)
-      {
-        t->waiting_lock = lock;
-        donate_priority (lock->holder);
-      }
-
-      intr_set_level (old_level);
-  }
-
-
+  enum intr_level old_level = intr_disable ();
+  if (lock->holder != NULL)
+    {
+      t->waiting_lock = lock;
+      donate_priority (lock->holder);
+    }
+  intr_set_level (old_level);
 
   sema_down (&lock->semaphore);
   lock->holder = thread_current ();
-  if (!thread_mlfqs)
-    t->waiting_lock = NULL;
+  t->waiting_lock = NULL;
 }
 
 /* Tries to acquires LOCK and returns true if successful or false
diff --git a/src/threads/thread.c b/src/threads/thread.c
index b551e3d..9e2fa41 100644
--- a/src/threads/thread.c
+++ b/src/threads/thread.c
@@ -74,6 +74,7 @@ static bool is_thread (struct thread *) UNUSED;
 static void *alloc_frame (struct thread *, size_t size);
 static int calculate_bsd_priority (fp32_t recent_cpu, int nice);
 static void update_recent_cpu (struct thread *t, void *aux UNUSED);
+static void recalculate_priority (struct thread *t);
 static void schedule (void);
 void thread_schedule_tail (struct thread *prev);
 static tid_t allocate_tid (void);
@@ -178,8 +179,11 @@ thread_tick (void)
         }
 
       /* Recent cpu was updated, update priority. */
-      if (ticks % PRI_UPDATE_FREQ == 0)
-        t->priority = calculate_bsd_priority (t->recent_cpu, t->nice);
+      if (t != idle_thread && ticks % PRI_UPDATE_FREQ == 0)
+        {
+          t->base_priority = calculate_bsd_priority (t->recent_cpu, t->nice);
+          recalculate_priority (t);
+        }
     }
 
   /* Enforce preemption. */
@@ -443,7 +447,7 @@ thread_set_priority (int new_base_priority)
     return;
 
   t->base_priority = new_base_priority;
-  thread_recalculate_priority ();
+  recalculate_priority (t);
 
   thread_yield ();
 }
@@ -467,17 +471,21 @@ update_recent_cpu (struct thread *t, void *aux UNUSED)
   t->recent_cpu
       = fp_add_int (fp_mul (recent_cpu_coeff, curr_recent_cpu), t->nice);
   // recent_cpu was updated, update priority.
-  t->priority = calculate_bsd_priority (t->recent_cpu, t->nice);
+  t->base_priority = calculate_bsd_priority (t->recent_cpu, t->nice);
+  recalculate_priority (t);
 }
+
 /* Recalculates the effective priority of the current thread. */
 void
 thread_recalculate_priority (void)
 {
   struct thread *t = thread_current ();
+  recalculate_priority (t);
+}
 
-  if (thread_mlfqs)
-    return;
-
+static void
+recalculate_priority (struct thread *t)
+{
   enum intr_level old_level = intr_disable ();
   t->priority = t->base_priority;
 
@@ -495,7 +503,6 @@ thread_recalculate_priority (void)
         t->priority = max_donated_priority;
     }
   intr_set_level (old_level);
-
 }
 
 /* Sets the current thread's nice value to NICE. */
@@ -506,10 +513,11 @@ thread_set_nice (int nice)
 
   struct thread *t = thread_current ();
   t->nice = nice;
-  int priority = calculate_bsd_priority (t->recent_cpu, t->nice);
+  t->base_priority = calculate_bsd_priority (t->recent_cpu, t->nice);
+  recalculate_priority (t);
   struct thread *next_t
       = list_entry (list_begin (&ready_list), struct thread, elem);
-  if (priority < next_t->priority)
+  if (t->priority < next_t->priority)
     thread_yield ();
 }
 
@@ -638,14 +646,14 @@ init_thread (struct thread *t, const char *name, int nice, int priority,
   t->stack = (uint8_t *) t + PGSIZE;
   t->magic = THREAD_MAGIC;
 
-  t->base_priority = priority;
+  t->base_priority
+      = thread_mlfqs ? calculate_bsd_priority (recent_cpu, nice) : priority;
   list_init (&t->donors_list);
   t->waiting_lock = NULL;
 
   t->nice = nice;
   t->recent_cpu = recent_cpu;
-  t->priority = thread_mlfqs ? calculate_bsd_priority (recent_cpu, nice)
-                             : t->base_priority;
+  t->priority = t->base_priority;
 
   old_level = intr_disable ();
   list_push_back (&all_list, &t->allelem);