diff --git a/base/commandLine.cpp b/base/commandLine.cpp
index 0c038cae4c4..2cd9025ad4d 100644
--- a/base/commandLine.cpp
+++ b/base/commandLine.cpp
@@ -140,6 +140,7 @@ void registerDefaults() {
 	ConfMan.registerDefault("music_volume", 127);
 	ConfMan.registerDefault("sfx_volume", 127);
 	ConfMan.registerDefault("speech_volume", 127);
+	ConfMan.registerDefault("speech_mute", false);
 	ConfMan.registerDefault("speech_mode", "3");
 	ConfMan.registerDefault("multi_midi", false);
 	ConfMan.registerDefault("native_mt32", false);