diff --git a/lib/bb/cooker.py b/lib/bb/cooker.py
index 939a99997..6318ef4a8 100644
--- a/lib/bb/cooker.py
+++ b/lib/bb/cooker.py
@@ -1459,7 +1459,6 @@ class BBCooker:
 
                     if t in task or getAllTaskSignatures:
                         try:
-                            rq.rqdata.prepare_task_hash(tid)
                             sig.append([pn, t, rq.rqdata.get_task_unihash(tid)])
                         except KeyError:
                             sig.append(self.getTaskSignatures(target, [t])[0])
diff --git a/lib/bb/runqueue.py b/lib/bb/runqueue.py
index 84a6f4172..999868dd7 100644
--- a/lib/bb/runqueue.py
+++ b/lib/bb/runqueue.py
@@ -1280,11 +1280,18 @@ class RunQueueData:
         dealtwith = set()
         todeal = set(self.runtaskentries)
         while todeal:
+            ready = set()
             for tid in todeal.copy():
                 if not (self.runtaskentries[tid].depends - dealtwith):
-                    dealtwith.add(tid)
-                    todeal.remove(tid)
-                    self.prepare_task_hash(tid)
+                    self.runtaskentries[tid].taskhash_deps = bb.parse.siggen.prep_taskhash(tid, self.runtaskentries[tid].depends, self.dataCaches)
+                    # get_taskhash for a given tid *must* be called before get_unihash* below
+                    self.runtaskentries[tid].hash = bb.parse.siggen.get_taskhash(tid, self.runtaskentries[tid].depends, self.dataCaches)
+                    ready.add(tid)
+            unihashes = bb.parse.siggen.get_unihashes(ready)
+            for tid in ready:
+                dealtwith.add(tid)
+                todeal.remove(tid)
+                self.runtaskentries[tid].unihash = unihashes[tid]
 
             bb.event.check_for_interrupts(self.cooker.data)
 
@@ -1301,11 +1308,6 @@ class RunQueueData:
         #self.dump_data()
         return len(self.runtaskentries)
 
-    def prepare_task_hash(self, tid):
-        self.runtaskentries[tid].taskhash_deps = bb.parse.siggen.prep_taskhash(tid, self.runtaskentries[tid].depends, self.dataCaches)
-        self.runtaskentries[tid].hash = bb.parse.siggen.get_taskhash(tid, self.runtaskentries[tid].depends, self.dataCaches)
-        self.runtaskentries[tid].unihash = bb.parse.siggen.get_unihash(tid)
-
     def dump_data(self):
         """
         Dump some debug information on the internal data structures