diff --git a/download/download_test.go b/download/download_test.go
new file mode 100644
index 0000000..8a7532a
--- /dev/null
+++ b/download/download_test.go
@@ -0,0 +1,25 @@
+package download
+
+import "testing"
+
+func TestClean(t *testing.T) {
+	cases := []struct {
+		path string
+		want string
+	}{
+		{"github.com/foo/bar", "github.com/foo/bar"},
+		{"https://github.com/foo/bar", "github.com/foo/bar"},
+		{"https://user@github.com/foo/bar", "github.com/foo/bar"},
+	}
+
+	for _, tt := range cases {
+		got, err := Clean(tt.path)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if got != tt.want {
+			t.Errorf("Clean(%q) = %q, want %q", tt.path, got, tt.want)
+		}
+	}
+}
diff --git a/download/proxy.go b/download/proxy.go
index 3e96628..d51124b 100644
--- a/download/proxy.go
+++ b/download/proxy.go
@@ -13,26 +13,45 @@ import (
 )
 
 const (
-	proxyLatestURL = "https://proxy.golang.org/%s/@latest"
-	proxyZipURL    = "https://proxy.golang.org/%s/@v/%s.zip"
-	proxyModURL    = "https://proxy.golang.org/%s/@v/%s.mod"
-	reposDir       = "_repos/src"
+	reposDir = "_repos/src"
 )
 
 type moduleVersion struct {
 	Version string
 }
 
+// ProxyClient is a client for the module proxy
+type ProxyClient struct {
+	URL string
+}
+
+// NewProxyClient returns a new ProxyClient
+func NewProxyClient(url string) ProxyClient {
+	return ProxyClient{URL: url}
+}
+
+func (c *ProxyClient) latestURL(module string) string {
+	return fmt.Sprintf("%s/%s/@latest", c.URL, module)
+}
+
+func (c *ProxyClient) zipURL(module, version string) string {
+	return fmt.Sprintf("%s/%s/@v/%s.zip", c.URL, module, version)
+}
+
+func (c *ProxyClient) modURL(module, version string) string {
+	return fmt.Sprintf("%s/%s/@v/%s.mod", c.URL, module, version)
+}
+
 // ModuleName gets the name of a module from the proxy
-func ModuleName(path string) (string, error) {
+func (c *ProxyClient) ModuleName(path string) (string, error) {
 	lowerPath := strings.ToLower(path)
 
-	ver, err := LatestVersion(path)
+	ver, err := c.LatestVersion(path)
 	if err != nil {
 		return "", err
 	}
 
-	u := fmt.Sprintf(proxyModURL, lowerPath, ver)
+	u := c.modURL(lowerPath, ver)
 	resp, err := http.Get(u)
 	if err != nil {
 		return "", err
@@ -62,9 +81,9 @@ func ModuleName(path string) (string, error) {
 }
 
 // LatestVersion gets the latest module version from the proxy
-func LatestVersion(path string) (string, error) {
+func (c *ProxyClient) LatestVersion(path string) (string, error) {
 	lowerPath := strings.ToLower(path)
-	u := fmt.Sprintf(proxyLatestURL, lowerPath)
+	u := fmt.Sprintf(c.latestURL(lowerPath))
 	resp, err := http.Get(u)
 	if err != nil {
 		return "", err
@@ -88,15 +107,15 @@ func LatestVersion(path string) (string, error) {
 }
 
 // ProxyDownload downloads a package from proxy.golang.org
-func ProxyDownload(path string) (string, error) {
+func (c *ProxyClient) ProxyDownload(path string) (string, error) {
 	lowerPath := strings.ToLower(path)
 
-	ver, err := LatestVersion(path)
+	ver, err := c.LatestVersion(path)
 	if err != nil {
 		return "", err
 	}
 
-	resp, err := http.Get(fmt.Sprintf(proxyZipURL, lowerPath, ver))
+	resp, err := http.Get(c.zipURL(lowerPath, ver))
 	if err != nil {
 		return "", err
 	}
diff --git a/download/proxy_test.go b/download/proxy_test.go
new file mode 100644
index 0000000..4f3f79f
--- /dev/null
+++ b/download/proxy_test.go
@@ -0,0 +1,54 @@
+package download
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestModuleName(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		u := r.URL
+		switch u.Path {
+		case "/github.com/user/module/@latest":
+			fmt.Fprintf(w, `{"Version":"v0.1.0","Time":"2019-08-07T08:30:46Z"}`)
+			return
+		case "/github.com/user/module/@v/v0.1.0.mod":
+			fmt.Fprintf(w, `module github.com/user/module`)
+			return
+		}
+	}))
+	defer ts.Close()
+
+	c := NewProxyClient(ts.URL)
+
+	got, err := c.ModuleName("github.com/user/module")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	want := "github.com/user/module"
+	if got != want {
+		t.Errorf("got module name = %q, want %q", got, want)
+	}
+}
+
+func TestLatestVersion(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, `{"Version":"v0.1.0","Time":"2019-08-07T08:30:46Z"}`)
+	}))
+	defer ts.Close()
+
+	c := NewProxyClient(ts.URL)
+
+	got, err := c.LatestVersion("github.com/user/module")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	want := "v0.1.0"
+	if got != want {
+		t.Errorf("got latest version = %q, want %q", got, want)
+	}
+}
diff --git a/handlers/check.go b/handlers/check.go
index a4fbc7e..2a711b7 100644
--- a/handlers/check.go
+++ b/handlers/check.go
@@ -28,7 +28,8 @@ func CheckHandler(w http.ResponseWriter, r *http.Request, db *badger.DB) {
 		return
 	}
 
-	moduleName, err := download.ModuleName(repo)
+	c := download.NewProxyClient("https://proxy.golang.org")
+	moduleName, err := c.ModuleName(repo)
 	if err != nil {
 		log.Println("ERROR: could not get module name:", err)
 	}
diff --git a/handlers/checks.go b/handlers/checks.go
index 168a1df..df9cb99 100644
--- a/handlers/checks.go
+++ b/handlers/checks.go
@@ -92,7 +92,8 @@ func newChecksResp(db *badger.DB, repo string, forceRefresh bool) (checksResp, e
 		}
 	}
 
-	ver, err := download.ProxyDownload(repo)
+	c := download.NewProxyClient("https://proxy.golang.org")
+	ver, err := c.ProxyDownload(repo)
 	if err != nil {
 		log.Println("ERROR:", err)
 		return checksResp{}, fmt.Errorf("could not download repo: %v", err)