diff --git a/internal/modproxy/modproxy.go b/internal/modproxy/modproxy.go
index a60fdfc..023e58f 100644
--- a/internal/modproxy/modproxy.go
+++ b/internal/modproxy/modproxy.go
@@ -26,6 +26,12 @@ import (
 // GOPROXY is the default module proxy
 var GOPROXY = "https://proxy.golang.org"
 
+func init() {
+	if s := os.Getenv("GOPROXY"); s != "" {
+		GOPROXY = s
+	}
+}
+
 // Module contains the module path and versions
 type Module struct {
 	Path     string
diff --git a/main.go b/main.go
index 6b97c6b..f6ed65f 100644
--- a/main.go
+++ b/main.go
@@ -34,12 +34,6 @@ The commands are:
     help    show this help text
 `
 
-func init() {
-	if goproxy := os.Getenv("GOPROXY"); goproxy != "" {
-		modproxy.GOPROXY = goproxy
-	}
-}
-
 func main() {
 	flag.Usage = func() {
 		fmt.Println(help)