diff --git a/main.go b/main.go
index f5abb65..121bc40 100644
--- a/main.go
+++ b/main.go
@@ -56,15 +56,15 @@ func main() {
 	}
 	uri := fs.Arg(0)
 
-	if strings.Index(uri, "/") != -1 {
+	if strings.Index(uri, "/") == -1 {
 		if !*updateFlag {
-			fmt.Println("provided arg must be a URI, unless using --update")
+			fmt.Printf("%q was not a URI and --update was not passed\n", uri)
 			return
 		}
 
 		pkg, ok := m.Packages[uri]
 		if !ok {
-			fmt.Println("arg was not a URI and didn't match an installed package")
+			fmt.Printf("%q was not a URI and didn't match an installed package\n", uri)
 			return
 		}
 		uri = pkg.Repo