diff --git a/cache_shared.go b/cache_shared.go
index 276f632..5d58141 100644
--- a/cache_shared.go
+++ b/cache_shared.go
@@ -53,13 +53,6 @@ type sharedCacheType struct {
 	// of the Go tool that the original "go build" invocation did.
 	GoCmd string
 
-	// GoVersion is a version of the Go toolchain currently being used,
-	// as reported by "go env GOVERSION" and compatible with go/version.
-	// Note that the version of Go that built the garble binary might be newer.
-	// Also note that a devel version like "go1.22-231f290e51" is
-	// currently represented as "go1.22", as the suffix is ignored by go/version.
-	GoVersion string
-
 	// Filled directly from "go env".
 	// Keep in sync with fetchGoEnv.
 	GoEnv struct {
diff --git a/main.go b/main.go
index 3635c5b..326d6ce 100644
--- a/main.go
+++ b/main.go
@@ -539,40 +539,35 @@ func goVersionOK() bool {
 		unsupportedGo = "go1.26"   // the first major version we don't support
 	)
 
-	// rxVersion looks for a version like "go1.2" or "go1.2.3" in `go env GOVERSION`.
-	rxVersion := regexp.MustCompile(`go\d+\.\d+(?:\.\d+)?`)
-
-	toolchainVersionFull := sharedCache.GoEnv.GOVERSION
-	sharedCache.GoVersion = rxVersion.FindString(toolchainVersionFull)
-	if sharedCache.GoVersion == "" {
+	toolchainVersion := sharedCache.GoEnv.GOVERSION
+	if toolchainVersion == "" {
 		// Go 1.15.x and older did not have GOVERSION yet; they are too old anyway.
 		fmt.Fprintf(os.Stderr, "Go version is too old; please upgrade to %s or newer\n", minGoVersion)
 		return false
 	}
 
-	if version.Compare(sharedCache.GoVersion, minGoVersion) < 0 {
-		fmt.Fprintf(os.Stderr, "Go version %q is too old; please upgrade to %s or newer\n", toolchainVersionFull, minGoVersion)
+	if version.Compare(toolchainVersion, minGoVersion) < 0 {
+		fmt.Fprintf(os.Stderr, "Go version %q is too old; please upgrade to %s or newer\n", toolchainVersion, minGoVersion)
 		return false
 	}
-	if version.Compare(sharedCache.GoVersion, unsupportedGo) >= 0 {
-		fmt.Fprintf(os.Stderr, "Go version %q is too new; Go linker patches aren't available for %s or later yet\n", toolchainVersionFull, unsupportedGo)
+	if version.Compare(toolchainVersion, unsupportedGo) >= 0 {
+		fmt.Fprintf(os.Stderr, "Go version %q is too new; Go linker patches aren't available for %s or later yet\n", toolchainVersion, unsupportedGo)
 		return false
 	}
 
 	// Ensure that the version of Go that built the garble binary is equal or
 	// newer than cache.GoVersionSemver.
-	builtVersionFull := cmp.Or(os.Getenv("GARBLE_TEST_GOVERSION"), runtime.Version())
-	builtVersion := rxVersion.FindString(builtVersionFull)
-	if builtVersion == "" {
+	builtVersion := cmp.Or(os.Getenv("GARBLE_TEST_GOVERSION"), runtime.Version())
+	if !version.IsValid(builtVersion) {
 		// If garble built itself, we don't know what Go version was used.
 		// Fall back to not performing the check against the toolchain version.
 		return true
 	}
-	if version.Compare(builtVersion, sharedCache.GoVersion) < 0 {
+	if version.Compare(builtVersion, toolchainVersion) < 0 {
 		fmt.Fprintf(os.Stderr, `
 garble was built with %q and can't be used with the newer %q; rebuild it with a command like:
     go install mvdan.cc/garble@latest
-`[1:], builtVersionFull, toolchainVersionFull)
+`[1:], builtVersion, toolchainVersion)
 		return false
 	}
 
diff --git a/testdata/script/goversion.txtar b/testdata/script/goversion.txtar
index e076c99..bb537c5 100644
--- a/testdata/script/goversion.txtar
+++ b/testdata/script/goversion.txtar
@@ -9,13 +9,12 @@ env TOOLCHAIN_GOVERSION=''
 ! exec garble build
 stderr 'Go version is too old; please upgrade to go1\.25\.0 or newer'
 
-# We should error on a devel version that's too old.
-# Note that they lacked the "goN.M-" prefix.
+# We should error on a devel version that's too old;
+# note that they started with the string "devel",
+# and very old ones didn't even have "goN.M" in them.
 env TOOLCHAIN_GOVERSION='devel +afb5fca Sun Aug 07 00:00:00 2020 +0000'
 ! exec garble build
-stderr 'Go version is too old; please upgrade to go1\.25\.0 or newer'
-
-# Another form of old version; with an old "goN.M-" prefix.
+stderr 'Go version "devel \+afb5.*2020.*" is too old; please upgrade to go1\.25\.0 or newer'
 env TOOLCHAIN_GOVERSION='devel go1.15-afb5fca Sun Aug 07 00:00:00 2020 +0000'
 ! exec garble build
 stderr 'Go version "devel go1\.15-.*2020.*" is too old; please upgrade to go1\.25\.0 or newer'
@@ -23,8 +22,8 @@ stderr 'Go version "devel go1\.15-.*2020.*" is too old; please upgrade to go1\.2
 # A current devel version should be fine.
 # Note that we don't look at devel version timestamps.
 env GARBLE_TEST_GOVERSION='go1.25.0'
-# TODO: temporarily disabled while we do not support tip.
-# env TOOLCHAIN_GOVERSION='devel go1.24-ad97d204f0 Sun Sep 12 16:46:58 2023 +0000'
+# TODO: we do not currently bother with supporting tip.
+# env TOOLCHAIN_GOVERSION='go version go1.26-devel_36863d6194 2025-10-17 01:07:59 -0700 linux/amd64'
 # ! exec garble build
 # stderr 'mocking the real build'
 
@@ -41,7 +40,7 @@ env TOOLCHAIN_GOVERSION='go1.28.2'
 stderr 'Go version "go1\.28\.2" is too new; Go linker patches aren''t available for go1\.26 or later yet'
 
 # We should accept custom devel strings.
-env TOOLCHAIN_GOVERSION='devel go1.25.0-somecustomversion'
+env TOOLCHAIN_GOVERSION='go1.25.0-somecustomversion'
 ! exec garble build
 stderr 'mocking the real build'