diff --git a/ChangeLog b/ChangeLog
index abf2995..cbed88a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2006-01-05  Karl Runge <runge@karlrunge.com>
+	* libvncserver/main.c: rfbRegisterProtocolExtension extMutex was
+	  never initialized.
+
 2005-12-24  Karl Runge <runge@karlrunge.com>
 	* x11vnc: enhance -passwdfile features, filetransfer on by default.
 
diff --git a/libvncserver/main.c b/libvncserver/main.c
index 41d70ea..972ce6f 100644
--- a/libvncserver/main.c
+++ b/libvncserver/main.c
@@ -61,6 +61,12 @@ void
 rfbRegisterProtocolExtension(rfbProtocolExtension* extension)
 {
 	rfbProtocolExtension* last;
+	static extMutex_initialized = 0;
+
+	if (! extMutex_initialized) {
+		INIT_MUTEX(extMutex);
+		extMutex_initialized = 1;
+	}
 
 	LOCK(extMutex);
 	last = extension;