diff --git a/bitbake/lib/bb/cache.py b/bitbake/lib/bb/cache.py
index ec7b023fc7..2361c5684d 100644
--- a/bitbake/lib/bb/cache.py
+++ b/bitbake/lib/bb/cache.py
@@ -395,7 +395,7 @@ class Cache(object):
         # It will be used later for deciding whether we
         # need extra cache file dump/load support
         self.mc = mc
-        self.logger = PrefixLoggerAdapter("Cache: %s: " % (mc if mc else "default"), logger)
+        self.logger = PrefixLoggerAdapter("Cache: %s: " % (mc if mc else ''), logger)
         self.caches_array = caches_array
         self.cachedir = self.data.getVar("CACHE")
         self.clean = set()
diff --git a/bitbake/lib/bb/cookerdata.py b/bitbake/lib/bb/cookerdata.py
index 1f447d30c2..65c153a5bb 100644
--- a/bitbake/lib/bb/cookerdata.py
+++ b/bitbake/lib/bb/cookerdata.py
@@ -346,7 +346,7 @@ class CookerDataBuilder(object):
     def _findLayerConf(self, data):
         return findConfigFile("bblayers.conf", data)
 
-    def parseConfigurationFiles(self, prefiles, postfiles, mc = "default"):
+    def parseConfigurationFiles(self, prefiles, postfiles, mc = ""):
         data = bb.data.createCopy(self.basedata)
         data.setVar("BB_CURRENT_MC", mc)
 
diff --git a/bitbake/lib/bb/tests/runqueue-tests/classes/base.bbclass b/bitbake/lib/bb/tests/runqueue-tests/classes/base.bbclass
index b57650d591..80b003b2b5 100644
--- a/bitbake/lib/bb/tests/runqueue-tests/classes/base.bbclass
+++ b/bitbake/lib/bb/tests/runqueue-tests/classes/base.bbclass
@@ -9,7 +9,7 @@ def stamptask(d):
     with open(stampname, "a+") as f:
         f.write(d.getVar("BB_UNIHASH") + "\n")
 
-    if d.getVar("BB_CURRENT_MC") != "default":
+    if d.getVar("BB_CURRENT_MC") != "":
         thistask = d.expand("${BB_CURRENT_MC}:${PN}:${BB_CURRENTTASK}")
     if thistask in d.getVar("SLOWTASKS").split():
         bb.note("Slowing task %s" % thistask)
diff --git a/bitbake/lib/bb/ui/uihelper.py b/bitbake/lib/bb/ui/uihelper.py
index 82913e0da8..e6983bd559 100644
--- a/bitbake/lib/bb/ui/uihelper.py
+++ b/bitbake/lib/bb/ui/uihelper.py
@@ -31,7 +31,7 @@ class BBUIHelper:
 
         if isinstance(event, bb.build.TaskStarted):
             tid = event._fn + ":" + event._task
-            if event._mc != "default":
+            if event._mc != "":
                 self.running_tasks[tid] = { 'title' : "mc:%s:%s %s" % (event._mc, event._package, event._task), 'starttime' : time.time(), 'pid' : event.pid }
             else:
                 self.running_tasks[tid] = { 'title' : "%s %s" % (event._package, event._task), 'starttime' : time.time(), 'pid' : event.pid }