diff --git a/common/rfb/SSecurityTLS.cxx b/common/rfb/SSecurityTLS.cxx
index 2ea84e0..9a34f3a 100644
--- a/common/rfb/SSecurityTLS.cxx
+++ b/common/rfb/SSecurityTLS.cxx
@@ -49,7 +49,7 @@
 
 static void debug_log(int level, const char* str)
 {
-  vlog.debug(str);
+  vlog.debug("[%d]: %s", level, str);
 }
 
 void SSecurityTLS::initGlobal()