diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
index da6e573..a444eae 100644
--- a/Source/WebCore/ChangeLog
+++ b/Source/WebCore/ChangeLog
@@ -1,3 +1,10 @@
+2019-10-21  Tim Horton  <timothy_horton@apple.com>
+
+        Fix the build
+
+        * platform/mock/MockAudioDestinationCocoa.cpp:
+        * platform/mock/MockAudioDestinationCocoa.h:
+
 2019-10-21  Myles C. Maxfield  <mmaxfield@apple.com>
 
         [Cocoa] Move ui-serif, ui-monospaced, and ui-rounded out from behind SPI
diff --git a/Source/WebCore/platform/mock/MockAudioDestinationCocoa.cpp b/Source/WebCore/platform/mock/MockAudioDestinationCocoa.cpp
index f42009c..863c4d5 100644
--- a/Source/WebCore/platform/mock/MockAudioDestinationCocoa.cpp
+++ b/Source/WebCore/platform/mock/MockAudioDestinationCocoa.cpp
@@ -43,6 +43,8 @@
 {
 }
 
+MockAudioDestinationCocoa::~MockAudioDestinationCocoa() = default;
+
 void MockAudioDestinationCocoa::start()
 {
     m_timer.startRepeating(Seconds { m_numberOfFramesToProcess / sampleRate() });
diff --git a/Source/WebCore/platform/mock/MockAudioDestinationCocoa.h b/Source/WebCore/platform/mock/MockAudioDestinationCocoa.h
index 5cd4d90..d4eae83 100644
--- a/Source/WebCore/platform/mock/MockAudioDestinationCocoa.h
+++ b/Source/WebCore/platform/mock/MockAudioDestinationCocoa.h
@@ -40,6 +40,7 @@
 public:
     static std::unique_ptr<AudioDestination> create(AudioIOCallback& callback, float sampleRate) { return makeUnique<MockAudioDestinationCocoa>(callback, sampleRate); }
     WEBCORE_EXPORT MockAudioDestinationCocoa(AudioIOCallback&, float sampleRate);
+    WEBCORE_EXPORT virtual ~MockAudioDestinationCocoa();
 
 private:
     void start() final;