diff --git a/firmware/drivers/ata.c b/firmware/drivers/ata.c
index 6a1db22919..87dacc3ed0 100644
--- a/firmware/drivers/ata.c
+++ b/firmware/drivers/ata.c
@@ -71,6 +71,74 @@
 static struct thread_entry *ata_thread_p = NULL;
 #endif
 
+#if defined(MAX_PHYS_SECTOR_SIZE) && MEM == 64
+/* Hack - what's the deal with 5g? */
+struct ata_lock
+{
+    struct thread_entry *thread;
+    int count;
+    volatile unsigned char locked;
+    IF_COP( struct corelock cl; )
+};
+
+static void ata_lock_init(struct ata_lock *l)
+{
+    corelock_init(&l->cl);
+    l->locked = 0;
+    l->count = 0;
+    l->thread = NULL;
+}
+
+static void ata_lock_lock(struct ata_lock *l)
+{
+    struct thread_entry * const current = thread_get_current();
+
+    if (current == l->thread)
+    {
+        l->count++;
+        return;
+    }
+
+    corelock_lock(&l->cl);
+
+    IF_PRIO( current->skip_count = -1; )
+
+    while (l->locked != 0)
+    {
+        corelock_unlock(&l->cl);
+        switch_thread();
+        corelock_lock(&l->cl);
+    }
+
+    l->locked = 1;
+    l->thread = current;
+    corelock_unlock(&l->cl);
+}
+
+static void ata_lock_unlock(struct ata_lock *l)
+{
+    if (l->count > 0)
+    {
+        l->count--;
+        return;
+    }
+
+    corelock_lock(&l->cl);
+
+    IF_PRIO( l->thread->skip_count = 0; )
+
+    l->thread = NULL;
+    l->locked = 0;
+
+    corelock_unlock(&l->cl);
+}
+
+#define mutex           ata_lock
+#define mutex_init      ata_lock_init
+#define mutex_lock      ata_lock_lock
+#define mutex_unlock    ata_lock_unlock
+#endif /* MAX_PHYS_SECTOR_SIZE */
+
 static struct mutex ata_mtx SHAREDBSS_ATTR;
 int ata_device; /* device 0 (master) or 1 (slave) */
 
diff --git a/firmware/thread.c b/firmware/thread.c
index 71656e1711..0f4273107f 100644
--- a/firmware/thread.c
+++ b/firmware/thread.c
@@ -161,6 +161,13 @@ void switch_thread(void)
  * Processor-specific section
  */
 
+#if defined(MAX_PHYS_SECTOR_SIZE) && MEM == 64
+/* Support a special workaround object for large-sector disks */
+#define IF_NO_SKIP_YIELD(...) __VA_ARGS__
+#else
+#define IF_NO_SKIP_YIELD(...)
+#endif
+
 #if defined(CPU_ARM)
 /*---------------------------------------------------------------------------
  * Start the thread running and terminate it if it returns
@@ -1945,8 +1952,9 @@ void switch_thread(void)
 #endif
 
 #ifdef HAVE_PRIORITY_SCHEDULING
+    IF_NO_SKIP_YIELD( if (thread->skip_count != -1) )
     /* Reset the value of thread's skip count */
-    thread->skip_count = 0;
+        thread->skip_count = 0;
 #endif
 
     for (;;)
@@ -2002,6 +2010,7 @@ void switch_thread(void)
                  * priority threads are runnable. The highest priority runnable
                  * thread(s) are never skipped. */
                 if (priority <= max ||
+                    IF_NO_SKIP_YIELD( thread->skip_count == -1 || )
                     (diff = priority - max, ++thread->skip_count > diff*diff))
                 {
                     cores[core].running = thread;
@@ -2146,7 +2155,8 @@ unsigned int wakeup_thread(struct thread_entry **list)
         if (bl == NULL)
         {
             /* No inheritance - just boost the thread by aging */
-            thread->skip_count = thread->priority;
+            IF_NO_SKIP_YIELD( if (thread->skip_count != -1) )
+                thread->skip_count = thread->priority;
             current = cores[CURRENT_CORE].running;
         }
         else