diff --git a/attachments_test.go b/attachments_test.go
index 0aba4210..b1ef8a1d 100644
--- a/attachments_test.go
+++ b/attachments_test.go
@@ -7,7 +7,6 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/facebookgo/ensure"
 	"github.com/mailgun/mailgun-go/v4"
 	"github.com/mailgun/mailgun-go/v4/events"
 	"github.com/stretchr/testify/require"
@@ -44,7 +43,7 @@ func TestMultipleAttachments(t *testing.T) {
 	t.Logf("New Email: %s Id: %s\n", msg, id)
 
 	e, err := findAcceptedMessage(mg, id)
-	ensure.NotNil(t, e)
+	require.NotNil(t, e)
 
 	require.Equal(t, e.ID, id)
 	require.Len(t, e.Message.Attachments, 2)
diff --git a/bounces_test.go b/bounces_test.go
index 169c61bb..18cf0641 100644
--- a/bounces_test.go
+++ b/bounces_test.go
@@ -11,8 +11,6 @@ import (
 
 	"github.com/mailgun/mailgun-go/v4"
 	"github.com/stretchr/testify/require"
-
-	"github.com/facebookgo/ensure"
 )
 
 func TestGetBounces(t *testing.T) {
@@ -39,7 +37,7 @@ func TestGetSingleBounce(t *testing.T) {
 	exampleEmail := fmt.Sprintf("%s@%s", strings.ToLower(randomString(64, "")),
 		os.Getenv("MG_DOMAIN"))
 	_, err := mg.GetBounce(ctx, exampleEmail)
-	ensure.NotNil(t, err)
+	require.NotNil(t, err)
 
 	var ure *mailgun.UnexpectedResponseError
 	require.ErrorAs(t, err, &ure)
diff --git a/events_test.go b/events_test.go
index e3bd7af2..18359c35 100644
--- a/events_test.go
+++ b/events_test.go
@@ -106,7 +106,7 @@ func TestEventPoller(t *testing.T) {
 		}
 	}
 	// Ensure we found our email
-	ensure.NotNil(t, it.Err())
+	require.NotNil(t, it.Err())
 	require.NotNil(t, accepted)
 	require.Equal(t, "user@"+testDomain, accepted.Recipient)
 }
diff --git a/mailing_lists_test.go b/mailing_lists_test.go
index 1b758f6e..54938699 100644
--- a/mailing_lists_test.go
+++ b/mailing_lists_test.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"testing"
 
-	"github.com/facebookgo/ensure"
 	"github.com/mailgun/mailgun-go/v4"
 	"github.com/stretchr/testify/require"
 )
@@ -90,7 +89,7 @@ func TestMailingListMembers(t *testing.T) {
 	theMember, err = mg.GetMember(ctx, "joe.user2@example.com", address)
 	require.NoError(t, err)
 	require.Equal(t, "Joe's Cool Account", theMember.Name)
-	ensure.NotNil(t, theMember.Subscribed)
+	require.NotNil(t, theMember.Subscribed)
 	require.True(t, *theMember.Subscribed)
 }
 
@@ -125,7 +124,7 @@ func TestMailingLists(t *testing.T) {
 		require.NoError(t, mg.DeleteMailingList(ctx, address))
 
 		_, err := mg.GetMailingList(ctx, address)
-		ensure.NotNil(t, err)
+		require.NotNil(t, err)
 	}()
 
 	actualCount := countLists()
diff --git a/messages_test.go b/messages_test.go
index 281049c5..1a0ccf85 100644
--- a/messages_test.go
+++ b/messages_test.go
@@ -260,7 +260,7 @@ func TestSendMGBatchFailRecipients(t *testing.T) {
 		err := m.AddRecipientAndVariables(toUser, nil)
 		// In case of error the SDK didn't send the message,
 		// OR the API didn't check for empty To: headers.
-		ensure.NotNil(t, err)
+		require.NotNil(t, err)
 	})
 }
 
@@ -417,7 +417,7 @@ func TestAddRecipientsError(t *testing.T) {
 	}
 
 	err := m.AddRecipient("recipient_1001@example.com")
-	ensure.NotNil(t, err)
+	require.NotNil(t, err)
 	require.EqualError(t, err, "recipient limit exceeded (max 1000)")
 }
 
@@ -491,7 +491,7 @@ func TestSendEOFError(t *testing.T) {
 
 	m := mailgun.NewMessage(fromUser, exampleSubject, exampleText, toUser)
 	_, _, err := mg.Send(context.Background(), m)
-	ensure.NotNil(t, err)
+	require.NotNil(t, err)
 	ensure.StringContains(t, err.Error(), "remote server prematurely closed connection: Post ")
 	ensure.StringContains(t, err.Error(), "EOF")
 }
@@ -553,7 +553,7 @@ func TestResendStored(t *testing.T) {
 	mg.SetAPIBase(srv.URL + "/v3")
 
 	msg, id, err := mg.ReSend(context.Background(), srv.URL+"/v3/some-url")
-	ensure.NotNil(t, err)
+	require.NotNil(t, err)
 	require.Equal(t, err.Error(), "must provide at least one recipient")
 
 	msg, id, err = mg.ReSend(context.Background(), srv.URL+"/v3/some-url", toUser)
diff --git a/routes_test.go b/routes_test.go
index d55cebb7..f4a7a31c 100644
--- a/routes_test.go
+++ b/routes_test.go
@@ -39,7 +39,7 @@ func TestRouteCRUD(t *testing.T) {
 	defer func() {
 		require.NoError(t, mg.DeleteRoute(ctx, newRoute.Id))
 		_, err = mg.GetRoute(ctx, newRoute.Id)
-		ensure.NotNil(t, err)
+		require.NotNil(t, err)
 	}()
 
 	newCount := countRoutes()
diff --git a/spam_complaints_test.go b/spam_complaints_test.go
index 1c59c07f..8a51c005 100644
--- a/spam_complaints_test.go
+++ b/spam_complaints_test.go
@@ -6,7 +6,6 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/facebookgo/ensure"
 	"github.com/mailgun/mailgun-go/v4"
 	"github.com/stretchr/testify/require"
 )
@@ -31,7 +30,7 @@ func TestGetComplaintFromRandomNoComplaint(t *testing.T) {
 	ctx := context.Background()
 
 	_, err := mg.GetComplaint(ctx, randomString(64, "")+"@example.com")
-	ensure.NotNil(t, err)
+	require.NotNil(t, err)
 
 	var ure *mailgun.UnexpectedResponseError
 	require.ErrorAs(t, err, &ure)
diff --git a/subaccounts_test.go b/subaccounts_test.go
index e4a50f84..d4ae8fd0 100644
--- a/subaccounts_test.go
+++ b/subaccounts_test.go
@@ -5,7 +5,6 @@ import (
 	"net/http"
 	"testing"
 
-	"github.com/facebookgo/ensure"
 	"github.com/mailgun/mailgun-go/v4"
 	"github.com/stretchr/testify/require"
 )
@@ -21,7 +20,7 @@ func TestListSubaccounts(t *testing.T) {
 	mg.SetAPIBase(server.URL())
 
 	iterator := mg.ListSubaccounts(nil)
-	ensure.NotNil(t, iterator)
+	require.NotNil(t, iterator)
 
 	ctx := context.Background()
 
@@ -43,7 +42,7 @@ func TestSubaccountDetails(t *testing.T) {
 	ctx := context.Background()
 
 	iterator := mg.ListSubaccounts(nil)
-	ensure.NotNil(t, iterator)
+	require.NotNil(t, iterator)
 
 	page := []mailgun.Subaccount{}
 	require.True(t, iterator.Next(context.Background(), &page))
@@ -51,7 +50,7 @@ func TestSubaccountDetails(t *testing.T) {
 
 	resp, err := mg.SubaccountDetails(ctx, page[0].Id)
 	require.NoError(t, err)
-	ensure.NotNil(t, resp)
+	require.NotNil(t, resp)
 }
 
 func TestSubaccountDetailsStatusNotFound(t *testing.T) {
@@ -77,7 +76,7 @@ func TestCreateSubaccount(t *testing.T) {
 
 	resp, err := mg.CreateSubaccount(ctx, testSubaccountName)
 	require.NoError(t, err)
-	ensure.NotNil(t, resp)
+	require.NotNil(t, resp)
 }
 
 func TestEnableSubaccountAlreadyEnabled(t *testing.T) {
diff --git a/tags_test.go b/tags_test.go
index 87dfe7d6..1cdea4bf 100644
--- a/tags_test.go
+++ b/tags_test.go
@@ -5,7 +5,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/facebookgo/ensure"
 	"github.com/mailgun/errors"
 	"github.com/mailgun/mailgun-go/v4"
 	"github.com/stretchr/testify/require"
@@ -24,8 +23,8 @@ func TestTags(t *testing.T) {
 	require.NoError(t, msg.AddTag("newsletter"))
 	require.NoError(t, msg.AddTag("homer"))
 	require.NoError(t, msg.AddTag("bart"))
-	ensure.NotNil(t, msg.AddTag("disco-steve"))
-	ensure.NotNil(t, msg.AddTag("newsletter"))
+	require.NotNil(t, msg.AddTag("disco-steve"))
+	require.NotNil(t, msg.AddTag("newsletter"))
 
 	ctx := context.Background()
 	// Create an email with some tags attached
@@ -60,7 +59,7 @@ func TestTags(t *testing.T) {
 	require.Equal(t, "homer", tag.Value)
 
 	_, err = mg.GetTag(ctx, "i-dont-exist")
-	ensure.NotNil(t, err)
+	require.NotNil(t, err)
 	require.Equal(t, 404, mailgun.GetStatusFromErr(err))
 }