diff --git a/modules/juce_core/threads/juce_TimeSliceThread.cpp b/modules/juce_core/threads/juce_TimeSliceThread.cpp
index 261fe85973..67a773c29c 100644
--- a/modules/juce_core/threads/juce_TimeSliceThread.cpp
+++ b/modules/juce_core/threads/juce_TimeSliceThread.cpp
@@ -89,6 +89,7 @@ void TimeSliceThread::moveToFrontOfQueue (TimeSliceClient* client)
 
 int TimeSliceThread::getNumClients() const
 {
+    const ScopedLock sl (listLock);
     return clients.size();
 }
 
@@ -98,6 +99,12 @@ TimeSliceClient* TimeSliceThread::getClient (const int i) const
     return clients[i];
 }
 
+bool TimeSliceThread::contains (const TimeSliceClient* c) const
+{
+    const ScopedLock sl (listLock);
+    return std::any_of (clients.begin(), clients.end(), [=] (auto* registered) { return registered == c; });
+}
+
 //==============================================================================
 TimeSliceClient* TimeSliceThread::getNextClient (int index) const
 {
diff --git a/modules/juce_core/threads/juce_TimeSliceThread.h b/modules/juce_core/threads/juce_TimeSliceThread.h
index fc4009adba..e4986481fa 100644
--- a/modules/juce_core/threads/juce_TimeSliceThread.h
+++ b/modules/juce_core/threads/juce_TimeSliceThread.h
@@ -131,6 +131,9 @@ public:
     /** Returns one of the registered clients. */
     TimeSliceClient* getClient (int index) const;
 
+    /** Returns true if the client is currently registered. */
+    bool contains (const TimeSliceClient*) const;
+
     //==============================================================================
    #ifndef DOXYGEN
     void run() override;