diff --git a/testdata/gofumpt-external/go.mod b/testdata/gofumpt-external/go.mod
index fb7adbc..fc08b20 100644
--- a/testdata/gofumpt-external/go.mod
+++ b/testdata/gofumpt-external/go.mod
@@ -1,11 +1,11 @@
 module test/gofumpt-external
 
-go 1.19
+go 1.22
 
-require mvdan.cc/gofumpt v0.3.2-0.20220627183521-8dda8068d9f3
+require mvdan.cc/gofumpt v0.6.1-0.20240717113859-88a300bbd6dc
 
 require (
-	github.com/google/go-cmp v0.5.8 // indirect
-	golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 // indirect
-	golang.org/x/tools v0.1.11 // indirect
+	github.com/google/go-cmp v0.6.0 // indirect
+	golang.org/x/mod v0.14.0 // indirect
+	golang.org/x/tools v0.17.0 // indirect
 )
diff --git a/testdata/gofumpt-external/go.sum b/testdata/gofumpt-external/go.sum
index da5c2a6..0e97614 100644
--- a/testdata/gofumpt-external/go.sum
+++ b/testdata/gofumpt-external/go.sum
@@ -1,13 +1,16 @@
-github.com/frankban/quicktest v1.14.3 h1:FJKSZTDHjyhriyC81FLQ0LY93eSai0ZyR/ZIkd3ZUKE=
-github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
-github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
-github.com/kr/pretty v0.3.0 h1:WgNl7dwNpEZ6jJ9k1snq4pZsg7DOEN8hP9Xw0Tsjwk0=
+github.com/go-quicktest/qt v1.101.0 h1:O1K29Txy5P2OK0dGo59b7b0LR6wKfIhttaAhHUyn7eI=
+github.com/go-quicktest/qt v1.101.0/go.mod h1:14Bz/f7NwaXPtdYEgzsx46kqSxVwTbzVZsDC26tQJow=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
-github.com/rogpeppe/go-internal v1.8.2-0.20220624104257-af73bbc5c731 h1:LkP6LNQyXrQoVVXMpb+sbb0iibcaOZH97feeh778heA=
-golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 h1:6zppjxzCulZykYSLyVDYbneBfbaBIQPYMevg0bEwv2s=
-golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
-golang.org/x/sys v0.0.0-20220624220833-87e55d714810 h1:rHZQSjJdAI4Xf5Qzeh2bBc5YJIkPFVM6oDtMFYmgws0=
-golang.org/x/tools v0.1.11 h1:loJ25fNOEhSXfHrpoGj91eCUThwdNX6u24rO1xnNteY=
-golang.org/x/tools v0.1.11/go.mod h1:SgwaegtQh8clINPpECJMqnxLv9I09HLqnW3RMqW0CA4=
-mvdan.cc/gofumpt v0.3.2-0.20220627183521-8dda8068d9f3 h1:Kk6yeaipDobigAr+NZqq37LjLN1q3LHSOpcaDLDwyoI=
-mvdan.cc/gofumpt v0.3.2-0.20220627183521-8dda8068d9f3/go.mod h1:TSc7K1qXnyCCK7LUmDAWp4UMntOys3CzN8ksMKaxFrE=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/rogpeppe/go-internal v1.12.0 h1:exVL4IDcn6na9z1rAb56Vxr+CgyK3nn3O+epU5NdKM8=
+github.com/rogpeppe/go-internal v1.12.0/go.mod h1:E+RYuTGaKKdloAfM02xzb0FW3Paa99yedzYV+kq4uf4=
+golang.org/x/mod v0.14.0 h1:dGoOF9QVLYng8IHTm7BAyWqCqSheQ5pYWGhzW00YJr0=
+golang.org/x/mod v0.14.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+golang.org/x/tools v0.17.0 h1:FvmRgNOcs3kOa+T20R1uhfP9F6HgG2mfxDv1vrx1Htc=
+golang.org/x/tools v0.17.0/go.mod h1:xsh6VxdV005rRVaS6SSAf9oiAqljS7UZUacMZ8Bnsps=
+mvdan.cc/gofumpt v0.6.1-0.20240717113859-88a300bbd6dc h1:XDr9kee1c8z5RRdwJnLWbAJ+x8NdkShxcqHSedJ6l+8=
+mvdan.cc/gofumpt v0.6.1-0.20240717113859-88a300bbd6dc/go.mod h1:txVFJy/Sc/mvaycET54pV8SW8gWxTlUuGHVEcncmNUo=
diff --git a/testdata/gofumpt-external/main.go b/testdata/gofumpt-external/main.go
index 22058e6..f94e74b 100644
--- a/testdata/gofumpt-external/main.go
+++ b/testdata/gofumpt-external/main.go
@@ -13,7 +13,7 @@ func main() {
 		panic(err)
 	}
 	formatted, err := format.Source(orig, format.Options{
-		LangVersion: "v1.16",
+		LangVersion: "go1.16",
 	})
 	if err != nil {
 		panic(err)
diff --git a/testdata/script/diagnose.txtar b/testdata/script/diagnose.txtar
index ec40644..0e533d2 100644
--- a/testdata/script/diagnose.txtar
+++ b/testdata/script/diagnose.txtar
@@ -42,8 +42,9 @@ cmp stdout foo.go.golden-devel
 # manually run something like go-internal/cmd/txtar-addmod reguarly.
 # Or teach goproxytest to serve a mock version of gofumpt from its local checkout.
 # Either way, both are relatively overkill for now.
+# Update this pseudo-version to master from time to time as needed.
 env GOBIN=${WORK}/bin
-env GOFUMPT_PUBLISHED_VERSION=v0.3.2-0.20220627183521-8dda8068d9f3
+env GOFUMPT_PUBLISHED_VERSION=v0.6.1-0.20240717113859-88a300bbd6dc
 
 # TODO: update these once the library fix hits master
 
@@ -95,8 +96,8 @@ package p
 -- foo.go.golden-released --
 package p
 
-//gofumpt:diagnose v0.3.2-0.20220627183521-8dda8068d9f3 -lang=go1.16 -modpath=test
+//gofumpt:diagnose version: v0.6.1-0.20240717113859-88a300bbd6dc (go1.18.29) flags: -lang=go1.16 -modpath=test
 -- foo.go.golden-external --
 package p
 
-//gofumpt:diagnose (devel) -lang=go1.16 -modpath=
+//gofumpt:diagnose version: v0.6.1-0.20240717113859-88a300bbd6dc (go1.18.29) flags: -lang=go1.16 -modpath=