diff --git a/gui/api.tcl b/gui/api.tcl
index e9918fc9..3c54bcea 100755
--- a/gui/api.tcl
+++ b/gui/api.tcl
@@ -75,7 +75,11 @@ proc receiveMessage { channel } {
     # read first four bytes of message header
     set more_data 1
     while { $more_data == 1 } {
-	set bytes [read $channel 4]
+        if { [catch { set bytes [read $channel 4] } e] } {
+            # in tcl8.6 this occurs during shutdown
+            #puts "channel closed: $e"
+            break;
+        }
 	if { [fblocked $channel]  == 1} {
 	    # 4 bytes not available yet
 	    break;
diff --git a/gui/core-gui.in b/gui/core-gui.in
index 2aeed1b2..714994fe 100755
--- a/gui/core-gui.in
+++ b/gui/core-gui.in
@@ -92,7 +92,7 @@ cd $LIBDIR
 core=$LIBDIR/core.tcl
 
 # locate wish8.5 binaries
-WISHLIST="/usr/local/bin/wish8.5 /usr/bin/wish8.5"
+WISHLIST="/usr/bin/wish8.6 /usr/local/bin/wish8.5 /usr/bin/wish8.5"
 for wishbin in $WISHLIST
 do
     if [ -x $wishbin ]