--- src/wsurf/wsurf.tcl.orig	2017-01-26 14:20:05.000000000 +0100
+++ src/wsurf/wsurf.tcl	2018-09-08 17:40:50.695124440 +0200
@@ -3126,7 +3126,12 @@
 
  foreach var [list inDev outDev PrintCmd PrintPVCmd linkFile tmpDir \
 		  defRate defEncoding defChannels recordLimit showLevel] {
-  set Info(Prefs,t,$var) $Info(Prefs,$var)
+  if {[info exists Info(Prefs,$var)]} {
+   set Info(Prefs,t,$var) $Info(Prefs,$var)
+  } else {
+   puts "Missing Info(Prefs,$var)"
+   set Info(Prefs,t,$var) {}
+  }
  }
  
  if {$Info(Prefs,linkFile)} {