@@ -18,16 +18,29 @@
 	"get" {
 		if {[llength $argv] < 4} {
 			print_help
 			exit 1
 		}
+
+		set existingexts [list]
 
 		set dir [lindex $argv 0]
 		set os [lindex $argv 1]
 		set cpu [lindex $argv 2]
 		set packages [lrange $argv 3 end]
-		set extsinfo [::teapotclient::download_extensions [file join $dir lib] $teapotservers $packages $os $cpu]
+
+		set newpackages [list]
+		foreach package $packages {
+			if {[string index $package 0] == "!"} {
+				lappend existingexts [string range $package 1 end]
+			} else {
+				lappend newpackages $package
+			}
+		}
+		set packages $newpackages
+
+		set extsinfo [::teapotclient::download_extensions [file join $dir lib] $teapotservers $packages $os $cpu $existingexts]
 		set exts [list]
 		puts "Fetched Extensions:"
 		foreach {ext extinfo} $extsinfo {
 			lappend exts $ext
 			puts "  $ext v[lindex $extinfo 0]"