diff --git a/Formula/certstrap.rb b/Formula/certstrap.rb
index ba6127e03f..10149406e1 100644
--- a/Formula/certstrap.rb
+++ b/Formula/certstrap.rb
@@ -14,7 +14,6 @@ class Certstrap < Formula
   depends_on "go" => :build
 
   def install
-    ENV["GO111MODULE"] = "on"
     ENV["GOPATH"] = buildpath
 
     dir = buildpath/"src/github.com/square/certstrap"