Index: softwareupdate/softwareupdate.tcl
==================================================================
--- softwareupdate/softwareupdate.tcl
+++ softwareupdate/softwareupdate.tcl
@@ -83,15 +83,18 @@
 
 	set changedata [$sparkledata selectNodes {string(//description/text())}]
 
 	set minOS [$sparkledata selectNodes -namespaces [list x "http://www.andymatuschak.org/xml-namespaces/sparkle"] {string(//x:minimumSystemVersion)}]
 
+
+	if {[tk windowingsystem] eq "aqua"] {
 	set hostOS [exec sw_vers -productVersion]
 
 	if {![package vsatisfies $hostOS $minOS]} {
 	    tk_messageBox -icon warning -message "Error!" -detail "$appname is not supported on Mac OS X $hostOS. The minimum supported OS version is $minOS." 
 	    return
+	}
 	}
 	
 	if {[expr $currentversion < $versionnumber]} {
 	    softwareupdate::updatePitch
 	} else {