diff --git a/src/common/SoundNull.hxx b/src/common/SoundNull.hxx
index 41bfbaef4..1670c909d 100644
--- a/src/common/SoundNull.hxx
+++ b/src/common/SoundNull.hxx
@@ -74,6 +74,16 @@ class SoundNull : public Sound
     */
     void mute(bool state) override { }
 
+    /**
+      Get the fragment size.
+    */
+    uInt32 getFragmentSize() const override { return 512; }
+
+    /**
+      Get the sample rate.
+    */
+    uInt32 getSampleRate() const override { return 31400; }
+
     /**
       Reset the sound device.
     */