diff --git a/lib/base/workqueue.cpp b/lib/base/workqueue.cpp
index c3259309a..615d21d3a 100644
--- a/lib/base/workqueue.cpp
+++ b/lib/base/workqueue.cpp
@@ -166,7 +166,7 @@ void WorkQueue::ReportExceptions(const String& facility) const
 	    << exceptions.size() << " error" << (exceptions.size() != 1 ? "s" : "");
 }
 
-size_t WorkQueue::GetLength(void)
+size_t WorkQueue::GetLength(void) const
 {
 	boost::mutex::scoped_lock lock(m_Mutex);
 
diff --git a/lib/base/workqueue.hpp b/lib/base/workqueue.hpp
index 871955d55..5d5de7465 100644
--- a/lib/base/workqueue.hpp
+++ b/lib/base/workqueue.hpp
@@ -52,7 +52,7 @@ public:
 
 	bool IsWorkerThread(void) const;
 
-	size_t GetLength(void);
+	size_t GetLength(void) const;
 
 	void SetExceptionCallback(const ExceptionCallback& callback);