--- maxima-5.9.1/interfaces/xmaxima/Tkmaxima/RunMaxima.tcl.orig	2004-06-21 15:46:32.000000000 -0700
+++ maxima-5.9.1/interfaces/xmaxima/Tkmaxima/RunMaxima.tcl	2006-04-04 22:33:51.000000000 -0700
@@ -451,13 +451,18 @@
 proc CMkill {  signal pid } {
     global maxima_priv tcl_platform
 
-    # Windows pids can be negative
     if {[string is int $pid]} {
-	gui status "Signaling $pid with $signal"
+        # Windows pids can be negative
 	if {$tcl_platform(platform) == "windows" } {
+	    gui status "Signaling $pid with $signal"
 	    exec $maxima_priv(kill) $signal $pid
 	} else {
-	    exec $maxima_priv(kill) $signal $pid
+            if {$pid > 1} {
+	        gui status "Signaling $pid with $signal"
+		exec $maxima_priv(kill) $signal $pid
+            } else {
+	        gui status "Bad PID $pid!! Refusing to send signal $signal"
+            }
 	}
     }
 }