diff --git a/google/internal/externalaccount/basecredentials.go b/google/internal/externalaccount/basecredentials.go
index b070133..dff0881 100644
--- a/google/internal/externalaccount/basecredentials.go
+++ b/google/internal/externalaccount/basecredentials.go
@@ -66,11 +66,11 @@ type CredentialSource struct {
 }
 
 // parse determines the type of CredentialSource needed
-func (c *Config) parse() baseCredentialSource {
+func (c *Config) parse(ctx context.Context) baseCredentialSource {
 	if c.CredentialSource.File != "" {
 		return fileCredentialSource{File: c.CredentialSource.File, Format: c.CredentialSource.Format}
 	} else if c.CredentialSource.URL != "" {
-		return urlCredentialSource{URL: c.CredentialSource.URL, Format: c.CredentialSource.Format}
+		return urlCredentialSource{URL: c.CredentialSource.URL, Format: c.CredentialSource.Format, ctx: ctx}
 	}
 	return nil
 }
@@ -89,7 +89,7 @@ type tokenSource struct {
 func (ts tokenSource) Token() (*oauth2.Token, error) {
 	conf := ts.conf
 
-	credSource := conf.parse()
+	credSource := conf.parse(ts.ctx)
 	if credSource == nil {
 		return nil, fmt.Errorf("oauth2/google: unable to parse credential source")
 	}
diff --git a/google/internal/externalaccount/filecredsource_test.go b/google/internal/externalaccount/filecredsource_test.go
index 0bc8048..56dd71e 100644
--- a/google/internal/externalaccount/filecredsource_test.go
+++ b/google/internal/externalaccount/filecredsource_test.go
@@ -5,6 +5,7 @@
 package externalaccount
 
 import (
+	"context"
 	"testing"
 )
 
@@ -55,7 +56,7 @@ func TestRetrieveFileSubjectToken(t *testing.T) {
 		tfc.CredentialSource = test.cs
 
 		t.Run(test.name, func(t *testing.T) {
-			out, err := tfc.parse().subjectToken()
+			out, err := tfc.parse(context.Background()).subjectToken()
 			if err != nil {
 				t.Errorf("Method subjectToken() errored.")
 			} else if test.want != out {
diff --git a/google/internal/externalaccount/urlcredsource.go b/google/internal/externalaccount/urlcredsource.go
index 0318d48..d3818be 100644
--- a/google/internal/externalaccount/urlcredsource.go
+++ b/google/internal/externalaccount/urlcredsource.go
@@ -5,39 +5,39 @@
 package externalaccount
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
+	"golang.org/x/oauth2"
 	"io"
 	"io/ioutil"
 	"net/http"
-	"strings"
 )
 
 type urlCredentialSource struct {
 	URL     string
 	Headers map[string]string
 	Format  format
+	ctx     context.Context
 }
 
 func (cs urlCredentialSource) subjectToken() (string, error) {
-	client := http.Client{}
-	req, err := http.NewRequest("GET", cs.URL, strings.NewReader(""))
+	client := oauth2.NewClient(cs.ctx, nil)
+	req, err := http.NewRequest("GET", cs.URL, nil)
 
 	for key, val := range cs.Headers {
 		req.Header.Add(key, val)
 	}
 	resp, err := client.Do(req)
 	if err != nil {
-		fmt.Errorf("oauth2/google: invalid response when retrieving subject token: %v", err)
-		return "", err
+		return "", fmt.Errorf("oauth2/google: invalid response when retrieving subject token: %v", err)
 	}
 	defer resp.Body.Close()
 
 	tokenBytes, err := ioutil.ReadAll(io.LimitReader(resp.Body, 1<<20))
 	if err != nil {
-		fmt.Errorf("oauth2/google: invalid body in subject token URL query: %v", err)
-		return "", err
+		return "", fmt.Errorf("oauth2/google: invalid body in subject token URL query: %v", err)
 	}
 
 	switch cs.Format.Type {
diff --git a/google/internal/externalaccount/urlcredsource_test.go b/google/internal/externalaccount/urlcredsource_test.go
index 5d66c2f..1deea05 100644
--- a/google/internal/externalaccount/urlcredsource_test.go
+++ b/google/internal/externalaccount/urlcredsource_test.go
@@ -14,7 +14,6 @@ import (
 var myURLToken = "testTokenValue"
 
 func TestRetrieveURLSubjectToken_Text(t *testing.T) {
-
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != "GET" {
 			t.Errorf("Unexpected request method, %v is found", r.Method)
@@ -35,12 +34,10 @@ func TestRetrieveURLSubjectToken_Text(t *testing.T) {
 	if out != myURLToken {
 		t.Errorf("got %v but want %v", out, myURLToken)
 	}
-
 }
 
 // Checking that retrieveSubjectToken properly defaults to type text
 func TestRetrieveURLSubjectToken_Untyped(t *testing.T) {
-
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != "GET" {
 			t.Errorf("Unexpected request method, %v is found", r.Method)
@@ -55,12 +52,11 @@ func TestRetrieveURLSubjectToken_Untyped(t *testing.T) {
 
 	out, err := tfc.parse().subjectToken()
 	if err != nil {
-		t.Fatalf("Failed to retrieve USRL subject token: %v", err)
+		t.Fatalf("Failed to retrieve URL subject token: %v", err)
 	}
 	if out != myURLToken {
 		t.Errorf("got %v but want %v", out, myURLToken)
 	}
-
 }
 
 func TestRetrieveURLSubjectToken_JSON(t *testing.T) {
@@ -86,12 +82,10 @@ func TestRetrieveURLSubjectToken_JSON(t *testing.T) {
 	tfc.CredentialSource = cs
 
 	out, err := tfc.parse().subjectToken()
-
 	if err != nil {
 		t.Fatalf("%v", err)
 	}
 	if out != myURLToken {
 		t.Errorf("got %v but want %v", out, myURLToken)
 	}
-
 }