diff --git a/mage.go b/mage.go
index fe19219..620e678 100644
--- a/mage.go
+++ b/mage.go
@@ -64,7 +64,7 @@ func Build() {
 
 		os.Mkdir(filepath.Join(d, goos), 0777)
 		for _, pkg := range []string{"route-httpagent", "route", "routed"} {
-			goBuild(ctx, append(os.Environ(), "GOOS="+goos), filepath.Join(d, goos), "cmd/"+pkg)
+			goBuild(ctx, []string{"GOOS=" + goos}, filepath.Join(d, goos), "cmd/"+pkg)
 			qod.Printlnf("built binary for %s for os %s", pkg, goos)
 		}
 	}