diff --git a/src/plugins/cppeditor/cppchecksymbols.h b/src/plugins/cppeditor/cppchecksymbols.h
index 0a528c484cb..5c03ff2def0 100644
--- a/src/plugins/cppeditor/cppchecksymbols.h
+++ b/src/plugins/cppeditor/cppchecksymbols.h
@@ -62,7 +62,7 @@ public:
         this->setRunnable(this);
         this->reportStarted();
         Future future = this->future();
-        QThreadPool::globalInstance()->start(this, QThread::IdlePriority);
+        QThreadPool::globalInstance()->start(this, QThread::LowestPriority);
         return future;
     }
 
diff --git a/src/plugins/cppeditor/cppeditor.cpp b/src/plugins/cppeditor/cppeditor.cpp
index 32f3ba68bbd..d2a3a9d90ed 100644
--- a/src/plugins/cppeditor/cppeditor.cpp
+++ b/src/plugins/cppeditor/cppeditor.cpp
@@ -2041,7 +2041,7 @@ bool SemanticHighlighter::isOutdated()
 
 void SemanticHighlighter::run()
 {
-    setPriority(QThread::IdlePriority);
+    setPriority(QThread::LowestPriority);
 
     forever {
         m_mutex.lock();
diff --git a/src/plugins/qmljseditor/qmljseditor.cpp b/src/plugins/qmljseditor/qmljseditor.cpp
index 0690151b34b..dd68aff7b52 100644
--- a/src/plugins/qmljseditor/qmljseditor.cpp
+++ b/src/plugins/qmljseditor/qmljseditor.cpp
@@ -1802,7 +1802,7 @@ bool SemanticHighlighter::isOutdated()
 
 void SemanticHighlighter::run()
 {
-    setPriority(QThread::IdlePriority);
+    setPriority(QThread::LowestPriority);
 
     forever {
         m_mutex.lock();