diff --git a/clientutil/balancer.go b/clientutil/balancer.go
index b70602c8bea87bfb2d53c048163f0711f9ee4154..ca926d005409e25722bd7d820ca750dfeefdb4a3 100644
--- a/clientutil/balancer.go
+++ b/clientutil/balancer.go
@@ -16,7 +16,7 @@ import (
 	"strings"
 	"time"
 
-	"github.com/cenkalti/backoff"
+	"github.com/cenkalti/backoff/v4"
 )
 
 // Our own narrow logger interface.
diff --git a/go.mod b/go.mod
index c1c3bf2f38a6e7cac95a828dad2f06f572da82c4..8603ba3ebe97fb7378d41cf9056204d2444eb850 100644
--- a/go.mod
+++ b/go.mod
@@ -6,7 +6,6 @@ require (
 	contrib.go.opencensus.io/exporter/zipkin v0.1.2
 	github.com/amoghe/go-crypt v0.0.0-20191109212615-b2ff80594b7f
 	github.com/bbrks/wrap/v2 v2.5.0
-	github.com/cenkalti/backoff v2.2.1+incompatible
 	github.com/cenkalti/backoff/v4 v4.1.0
 	github.com/coreos/go-systemd/v22 v22.1.0
 	github.com/emersion/go-textwrapper v0.0.0-20200911093747-65d896831594
@@ -17,16 +16,12 @@ require (
 	github.com/gorilla/handlers v1.5.1
 	github.com/lunixbochs/struc v0.0.0-20200707160740-784aaebc1d40
 	github.com/miscreant/miscreant.go v0.0.0-20200214223636-26d376326b75
-	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/openzipkin/zipkin-go v0.2.5
-	github.com/pierrec/lz4 v2.0.5+incompatible // indirect
 	github.com/prometheus/client_golang v1.9.0
 	github.com/russross/blackfriday/v2 v2.1.0
 	github.com/theckman/go-flock v0.8.0
 	github.com/tstranex/u2f v1.0.0
 	go.opencensus.io v0.22.5
 	golang.org/x/crypto v0.0.0-20201221181555-eec23a3978ad
-	golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421 // indirect
 	golang.org/x/sync v0.0.0-20201207232520-09787c993a3a
-	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
 )
diff --git a/go.sum b/go.sum
index 16d04779143437f7fb03ec06d1a4c8b91b376536..63cf02b1a549487e1c763111e84ff2c99b34bb46 100644
--- a/go.sum
+++ b/go.sum
@@ -36,6 +36,7 @@ github.com/bgentry/speakeasy v0.1.0/go.mod h1:+zsyZBPWlz7T6j88CTgSN5bM796AkVf0kB
 github.com/casbin/casbin/v2 v2.1.2/go.mod h1:YcPU1XXisHhLzuxH9coDNf2FbKpjGlbCg3n9yuLkIJQ=
 github.com/cenkalti/backoff v2.2.1+incompatible h1:tNowT99t7UNflLxfYYSlKYsBpXdEet03Pg2g16Swow4=
 github.com/cenkalti/backoff v2.2.1+incompatible/go.mod h1:90ReRw6GdpyfrHakVjL/QHaoyV4aDUVVkXQJJJ3NXXM=
+github.com/cenkalti/backoff/v4 v4.1.0 h1:c8LkOFQTzuO0WBM/ae5HdGQuZPfPxp7lqBRwQRm4fSc=
 github.com/cenkalti/backoff/v4 v4.1.0/go.mod h1:scbssz8iZGpm3xbr14ovlUdkxfGXNInqkPWOWmG2CLw=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/cespare/xxhash/v2 v2.1.1 h1:6MnRN8NT7+YBpUIWxHtefFZOKTAPgGjpQSxqLNn0+qY=
diff --git a/ldap/pool.go b/ldap/pool.go
index 9092c364d935276dd43d9644c7440658eb57b982..a13887d3e190ab10da0462abf36e313677b936ac 100644
--- a/ldap/pool.go
+++ b/ldap/pool.go
@@ -7,7 +7,7 @@ import (
 	"net/url"
 	"time"
 
-	"github.com/cenkalti/backoff"
+	"github.com/cenkalti/backoff/v4"
 	"github.com/go-ldap/ldap/v3"
 	"github.com/prometheus/client_golang/prometheus"
 	"go.opencensus.io/trace"