diff --git a/filters.go b/filters.go
index 2ec7d0b..ddae2da 100644
--- a/filters.go
+++ b/filters.go
@@ -10,7 +10,7 @@ import (
 	"time"
 	"unicode/utf8"
 
-	"github.com/flosch/pongo2"
+	"github.com/flosch/pongo2/v4"
 
 	"github.com/extemporalgenome/slug"
 	"github.com/flosch/go-humanize"
diff --git a/go.mod b/go.mod
index dc12677..138d558 100644
--- a/go.mod
+++ b/go.mod
@@ -6,9 +6,10 @@ require (
 	github.com/extemporalgenome/slug v0.0.0-20150414033109-0320c85e32e0
 	github.com/flosch/go-humanize v0.0.0-20140728123800-3ba51eabe506
 	github.com/flosch/pongo2 v0.0.0-20200529170236-5abacdfa4915
+	github.com/flosch/pongo2/v4 v4.0.2 // indirect
 	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
 	github.com/russross/blackfriday/v2 v2.0.1
 	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
 	golang.org/x/text v0.3.3 // indirect
-	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f
+	gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b
 )
diff --git a/go.sum b/go.sum
index 99a7b4d..67dcc83 100644
--- a/go.sum
+++ b/go.sum
@@ -4,6 +4,12 @@ github.com/flosch/go-humanize v0.0.0-20140728123800-3ba51eabe506 h1:tN043XK9BV76
 github.com/flosch/go-humanize v0.0.0-20140728123800-3ba51eabe506/go.mod h1:pSiPkAThBLWmIzJ2fukUGkcxxWR4HoLT7Bp8/krrl5g=
 github.com/flosch/pongo2 v0.0.0-20200529170236-5abacdfa4915 h1:rNVrewdFbSujcoKZifC6cHJfqCTbCIR7XTLHW5TqUWU=
 github.com/flosch/pongo2 v0.0.0-20200529170236-5abacdfa4915/go.mod h1:fB4mx6dzqFinCxIf3a7Mf5yLk+18Bia9mPAnuejcvDA=
+github.com/flosch/pongo2/v4 v4.0.2 h1:gv+5Pe3vaSVmiJvh/BZa82b7/00YUGm0PIyVVLop0Hw=
+github.com/flosch/pongo2/v4 v4.0.2/go.mod h1:B5ObFANs/36VwxxlgKpdchIJHMvHB562PW+BWPhwZD8=
+github.com/go-check/check v0.0.0-20180628173108-788fd7840127/go.mod h1:9ES+weclKsC9YodN5RgxqK/VD9HM9JsCSh7rNhMZE98=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
 github.com/russross/blackfriday/v2 v2.0.1 h1:lPqVAte+HuHNfhJ/0LC98ESWRz8afy9tM/0RK8m9o+Q=
@@ -13,5 +19,7 @@ github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeV
 golang.org/x/text v0.3.3 h1:cokOdA+Jmi5PJGXLlLllQSgYigAEfHXJAERHVMaCc2k=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f h1:BLraFXnmrev5lT+xlilqcH8XK9/i0At2xKjWk4p6zsU=
 gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=