diff --git a/transport/http/client.go b/transport/http/client.go
index 92d3292fc..eca566300 100644
--- a/transport/http/client.go
+++ b/transport/http/client.go
@@ -12,9 +12,14 @@ import (
 	"github.com/go-kit/kit/endpoint"
 )
 
+// HTTPClient is an interface that models *http.Client.
+type HTTPClient interface {
+	Do(req *http.Request) (*http.Response, error)
+}
+
 // Client wraps a URL and provides a method that implements endpoint.Endpoint.
 type Client struct {
-	client         *http.Client
+	client         HTTPClient
 	method         string
 	tgt            *url.URL
 	enc            EncodeRequestFunc
@@ -54,7 +59,7 @@ type ClientOption func(*Client)
 
 // SetClient sets the underlying HTTP client used for requests.
 // By default, http.DefaultClient is used.
-func SetClient(client *http.Client) ClientOption {
+func SetClient(client HTTPClient) ClientOption {
 	return func(c *Client) { c.client = client }
 }
 
diff --git a/transport/http/client_test.go b/transport/http/client_test.go
index d66381000..e31d201cc 100644
--- a/transport/http/client_test.go
+++ b/transport/http/client_test.go
@@ -1,6 +1,7 @@
 package http_test
 
 import (
+	"bytes"
 	"context"
 	"io"
 	"io/ioutil"
@@ -252,6 +253,43 @@ func TestEncodeJSONRequest(t *testing.T) {
 	}
 }
 
+func TestSetClient(t *testing.T) {
+	var (
+		encode = func(context.Context, *http.Request, interface{}) error { return nil }
+		decode = func(_ context.Context, r *http.Response) (interface{}, error) {
+			t, err := ioutil.ReadAll(r.Body)
+			if err != nil {
+				return nil, err
+			}
+			return string(t), nil
+		}
+	)
+
+	testHttpClient := httpClientFunc(func(req *http.Request) (*http.Response, error) {
+		return &http.Response{
+			StatusCode: http.StatusOK,
+			Request:    req,
+			Body:       ioutil.NopCloser(bytes.NewBufferString("hello, world!")),
+		}, nil
+	})
+
+	client := httptransport.NewClient(
+		"GET",
+		&url.URL{},
+		encode,
+		decode,
+		httptransport.SetClient(testHttpClient),
+	).Endpoint()
+
+	resp, err := client(context.Background(), nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if r, ok := resp.(string); !ok || r != "hello, world!" {
+		t.Fatal("Expected response to be 'hello, world!' string")
+	}
+}
+
 func mustParse(s string) *url.URL {
 	u, err := url.Parse(s)
 	if err != nil {
@@ -265,3 +303,9 @@ type enhancedRequest struct {
 }
 
 func (e enhancedRequest) Headers() http.Header { return http.Header{"X-Edward": []string{"Snowden"}} }
+
+type httpClientFunc func(req *http.Request) (*http.Response, error)
+
+func (f httpClientFunc) Do(req *http.Request) (*http.Response, error) {
+	return f(req)
+}
diff --git a/transport/http/jsonrpc/client.go b/transport/http/jsonrpc/client.go
index de17fd5bd..4d8fe303d 100644
--- a/transport/http/jsonrpc/client.go
+++ b/transport/http/jsonrpc/client.go
@@ -15,7 +15,7 @@ import (
 
 // Client wraps a JSON RPC method and provides a method that implements endpoint.Endpoint.
 type Client struct {
-	client *http.Client
+	client httptransport.HTTPClient
 
 	// JSON RPC endpoint URL
 	tgt *url.URL
@@ -86,7 +86,7 @@ type ClientOption func(*Client)
 
 // SetClient sets the underlying HTTP client used for requests.
 // By default, http.DefaultClient is used.
-func SetClient(client *http.Client) ClientOption {
+func SetClient(client httptransport.HTTPClient) ClientOption {
 	return func(c *Client) { c.client = client }
 }