diff --git a/README.md b/README.md
index d572972..e152b30 100644
--- a/README.md
+++ b/README.md
@@ -651,7 +651,7 @@ package p
 $ gofumpt f.go
 package p
 
-//gofumpt:diagnose v0.1.1-0.20211103104632-bdfa3b02e50a -lang=v1.16
+//gofumpt:diagnose v0.1.1-0.20211103104632-bdfa3b02e50a -lang=go1.16
 ```
 
 ### License
diff --git a/format/format.go b/format/format.go
index 64d4fe0..e81420c 100644
--- a/format/format.go
+++ b/format/format.go
@@ -12,6 +12,7 @@ import (
 	"go/ast"
 	"go/parser"
 	"go/token"
+	goversion "go/version"
 	"os"
 	"reflect"
 	"regexp"
@@ -23,7 +24,6 @@ import (
 	"unicode/utf8"
 
 	"github.com/google/go-cmp/cmp"
-	"golang.org/x/mod/semver"
 	"golang.org/x/tools/go/ast/astutil"
 
 	"mvdan.cc/gofumpt/internal/govendor/go/format"
@@ -32,26 +32,25 @@ import (
 
 // Options is the set of formatting options which affect gofumpt.
 type Options struct {
-	// TODO: link to the go/version docs once Go 1.22 is out.
-	// The old semver docs said:
-	//
-	// LangVersion is treated as a semantic version, which may start with a "v"
-	// prefix. Like Go versions, it may also be incomplete; "1.14" is equivalent
-	// to "1.14.0". When empty, it is equivalent to "v1", to not use language
-	// features which could break programs.
-
 	// LangVersion is the Go version a piece of code is written in.
 	// The version is used to decide whether to apply formatting
 	// rules which require new language features.
-	// When inside a Go module, LangVersion should typically be:
+	// When empty, a default of go1 is assumed.
+	// Otherwise, the version must satisfy [go/version.IsValid].
+	//
+	// When formatting a Go module, LangVersion should typically be
 	//
-	//     go mod edit -json | jq -r '.Go'
+	//     go list -m -f {{.GoVersion}}
+	//
+	// with a "go" prefix, or the equivalent from `go mod edit -json`.
 	LangVersion string
 
 	// ModulePath corresponds to the Go module path which contains the source
-	// code being formatted. When inside a Go module, ModulePath should be:
+	// code being formatted. When formatting a Go module, ModulePath should be
+	//
+	//     go list -m -f {{.Path}}
 	//
-	//     go mod edit -json | jq -r '.Module.Path'
+	// or the equivalent from `go mod edit -json`.
 	//
 	// ModulePath is used for formatting decisions like what import paths are
 	// considered to be not part of the standard library. When empty, the source
@@ -86,26 +85,21 @@ func Source(src []byte, opts Options) ([]byte, error) {
 	return buf.Bytes(), nil
 }
 
-var rxGoVersionMajorMinor = regexp.MustCompile(`^(v|go)?([1-9]+)\.([0-9]+)`)
-
 // File modifies a file and fset in place to follow gofumpt's format. The
 // changes might include manipulating adding or removing newlines in fset,
 // modifying the position of nodes, or modifying literal values.
 func File(fset *token.FileSet, file *ast.File, opts Options) {
 	simplify(file)
 
-	// TODO: replace this hacky mess with go/version once we can rely on Go 1.22,
-	// as well as replacing our uses of the semver package.
-	// In particular, we likely want to allow any of 1.21, 1.21.2, or go1.21rc3,
-	// but we can rely on go/version.Lang to validate and normalize.
 	if opts.LangVersion == "" {
-		opts.LangVersion = "v1.0"
-	}
-	m := rxGoVersionMajorMinor.FindStringSubmatch(opts.LangVersion)
-	if m == nil {
-		panic(fmt.Sprintf("invalid Go version: %q", opts.LangVersion))
+		opts.LangVersion = "go1"
+	} else {
+		lang := goversion.Lang(opts.LangVersion)
+		if lang == "" {
+			panic(fmt.Sprintf("invalid Go version: %q", opts.LangVersion))
+		}
+		opts.LangVersion = lang
 	}
-	opts.LangVersion = "v" + m[2] + "." + m[3]
 	f := &fumpter{
 		file:    fset.File(file.Pos()),
 		fset:    fset,
@@ -680,8 +674,8 @@ func (f *fumpter) applyPre(c *astutil.Cursor) {
 		}
 
 	case *ast.BasicLit:
-		// Octal number literals were introduced in 1.13.
-		if semver.Compare(f.LangVersion, "v1.13") >= 0 {
+		// Octal number literals were introduced in Go 1.13.
+		if goversion.Compare(f.LangVersion, "go1.13") >= 0 {
 			if node.Kind == token.INT && rxOctalInteger.MatchString(node.Value) {
 				node.Value = "0o" + node.Value[1:]
 				c.Replace(node)
diff --git a/format/fuzz_test.go b/format/fuzz_test.go
index 8dfa113..649c20c 100644
--- a/format/fuzz_test.go
+++ b/format/fuzz_test.go
@@ -26,9 +26,9 @@ func FuzzFormat(f *testing.F) {
 		for _, file := range archive.Files {
 			f.Logf("adding %s from %s", file.Name, path)
 			if strings.HasSuffix(file.Name, ".go") || strings.Contains(file.Name, ".go.") {
-				f.Add(string(file.Data), int8(18), false) // -lang=1.18
-				f.Add(string(file.Data), int8(1), false)  // -lang=1.1
-				f.Add(string(file.Data), int8(18), true)  // -lang=1.18 -extra
+				f.Add(string(file.Data), int8(18), false) // -lang=go1.18
+				f.Add(string(file.Data), int8(1), false)  // -lang=go1.1
+				f.Add(string(file.Data), int8(18), true)  // -lang=go1.18 -extra
 			}
 		}
 	}
@@ -40,7 +40,7 @@ func FuzzFormat(f *testing.F) {
 		// TODO: also fuzz Options.ModulePath
 		opts := Options{ExtraRules: extraRules}
 		if majorVersion >= 0 {
-			opts.LangVersion = fmt.Sprintf("1.%d", majorVersion)
+			opts.LangVersion = fmt.Sprintf("go1.%d", majorVersion)
 		}
 
 		orig := []byte(src)
diff --git a/go.mod b/go.mod
index c973b93..e862bba 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module mvdan.cc/gofumpt
 
-go 1.21
+go 1.22
 
 require (
 	github.com/go-quicktest/qt v1.101.0
diff --git a/gofmt.go b/gofmt.go
index 384795a..873a74d 100644
--- a/gofmt.go
+++ b/gofmt.go
@@ -96,7 +96,7 @@ func usage() {
 	-w        write result to (source) file instead of stdout
 	-extra    enable extra rules which should be vetted by a human
 
-	-lang       str    target Go version in the form "1.X" (default from go.mod)
+	-lang       str    target Go version in the form "go1.X" (default from go.mod)
 	-modpath    str    Go module path containing the source file (default from go.mod)
 `)
 }
@@ -298,7 +298,7 @@ func processFile(filename string, info fs.FileInfo, in io.Reader, r *reporter, e
 		if ok && mod != nil {
 			mod := mod.(*module)
 			if lang == "" {
-				lang = mod.Go
+				lang = "go" + mod.Go
 			}
 			if modpath == "" {
 				modpath = mod.Module.Path
diff --git a/testdata/script/diagnose.txtar b/testdata/script/diagnose.txtar
index 6bbcb8f..ec40644 100644
--- a/testdata/script/diagnose.txtar
+++ b/testdata/script/diagnose.txtar
@@ -14,7 +14,7 @@ cmp stdout foo.go.golden
 exec gofumpt -extra foo.go
 cmp stdout foo.go.golden-extra
 
-exec gofumpt -lang=1.0 foo.go
+exec gofumpt -lang=go1 foo.go
 cmp stdout foo.go.golden-lang
 
 exec gofumpt -d nochange.go
@@ -79,24 +79,24 @@ package p
 -- foo.go.golden --
 package p
 
-//gofumpt:diagnose version: v0.0.0-20220727155840-8dda8068d9f3 (go1.18.29) flags: -lang=v1.16 -modpath=test
+//gofumpt:diagnose version: v0.0.0-20220727155840-8dda8068d9f3 (go1.18.29) flags: -lang=go1.16 -modpath=test
 -- foo.go.golden-devel --
 package p
 
-//gofumpt:diagnose version: (devel) (go1.18.29) flags: -lang=v1.16 -modpath=test
+//gofumpt:diagnose version: (devel) (go1.18.29) flags: -lang=go1.16 -modpath=test
 -- foo.go.golden-extra --
 package p
 
-//gofumpt:diagnose version: v0.0.0-20220727155840-8dda8068d9f3 (go1.18.29) flags: -lang=v1.16 -modpath=test -extra
+//gofumpt:diagnose version: v0.0.0-20220727155840-8dda8068d9f3 (go1.18.29) flags: -lang=go1.16 -modpath=test -extra
 -- foo.go.golden-lang --
 package p
 
-//gofumpt:diagnose version: v0.0.0-20220727155840-8dda8068d9f3 (go1.18.29) flags: -lang=v1.0 -modpath=test
+//gofumpt:diagnose version: v0.0.0-20220727155840-8dda8068d9f3 (go1.18.29) flags: -lang=go1 -modpath=test
 -- foo.go.golden-released --
 package p
 
-//gofumpt:diagnose v0.3.2-0.20220627183521-8dda8068d9f3 -lang=v1.16 -modpath=test
+//gofumpt:diagnose v0.3.2-0.20220627183521-8dda8068d9f3 -lang=go1.16 -modpath=test
 -- foo.go.golden-external --
 package p
 
-//gofumpt:diagnose (devel) -lang=v1.16 -modpath=
+//gofumpt:diagnose (devel) -lang=go1.16 -modpath=
diff --git a/testdata/script/gomod.txtar b/testdata/script/gomod.txtar
index 90f13a8..e3c0258 100644
--- a/testdata/script/gomod.txtar
+++ b/testdata/script/gomod.txtar
@@ -1,10 +1,10 @@
 # Test various edge cases with go.mod files.
 
 exec gofumpt toolchain-stable/a.go
-stdout '//gofumpt:diagnose.* -lang=v1.21'
+stdout '//gofumpt:diagnose.* -lang=go1.21'
 
 exec gofumpt toolchain-unstable/a.go
-stdout '//gofumpt:diagnose.* -lang=v1.21'
+stdout '//gofumpt:diagnose.* -lang=go1.21'
 
 -- toolchain-stable/go.mod --
 module a
diff --git a/testdata/script/octal-literals.txtar b/testdata/script/octal-literals.txtar
index 0408dda..3577a72 100644
--- a/testdata/script/octal-literals.txtar
+++ b/testdata/script/octal-literals.txtar
@@ -3,7 +3,7 @@ exec gofumpt -l .
 ! stdout .
 
 # We can give an explicitly newer version.
-exec gofumpt -lang=1.13 -l .
+exec gofumpt -lang=go1.13 -l .
 stdout -count=1 'foo\.go'
 stdout -count=1 'nested[/\\]nested\.go'
 
@@ -20,7 +20,7 @@ exec gofumpt -d foo.go.golden
 ! stdout .
 
 # We can give an explicitly older version, too
-exec gofumpt -lang=1.0 -l .
+exec gofumpt -lang=go1.0 -l .
 ! stdout .
 
 -- go.mod --