diff --git a/src/go/version/version.go b/src/go/version/version.go
index 466c809..6b8ee67 100644
--- a/src/go/version/version.go
+++ b/src/go/version/version.go
@@ -2,9 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package version provides operations on [Go versions].
+// Package version provides operations on [Go versions]
+// in [Go toolchain name syntax]: strings like
+// "go1.20", "go1.21.0", "go1.22rc2", and "go1.23.4-bigcorp".
 //
 // [Go versions]: https://go.dev/doc/toolchain#version
+// [Go toolchain name syntax]: https://go.dev/doc/toolchain#name
 package version // import "go/version"
 
 import (
@@ -12,9 +15,10 @@
 	"strings"
 )
 
-// stripGo converts from a "go1.21" version to a "1.21" version.
+// stripGo converts from a "go1.21-bigcorp" version to a "1.21" version.
 // If v does not start with "go", stripGo returns the empty string (a known invalid version).
 func stripGo(v string) string {
+	v, _, _ = strings.Cut(v, "-") // strip -bigcorp suffix.
 	if len(v) < 2 || v[:2] != "go" {
 		return ""
 	}
@@ -50,8 +54,6 @@
 // valid versions and equal to each other.
 // The language version "go1.21" compares less than the
 // release candidate and eventual releases "go1.21rc1" and "go1.21.0".
-// Custom toolchain suffixes are ignored during comparison:
-// "go1.21.0" and "go1.21.0-bigcorp" are equal.
 func Compare(x, y string) int {
 	return gover.Compare(stripGo(x), stripGo(y))
 }
diff --git a/src/go/version/version_test.go b/src/go/version/version_test.go
index 7c12e7f..ad83a25 100644
--- a/src/go/version/version_test.go
+++ b/src/go/version/version_test.go
@@ -23,13 +23,16 @@
 	{"go1.19", "go1.19.0", 0},
 	{"go1.19rc1", "go1.19", -1},
 	{"go1.20", "go1.20.0", 0},
+	{"go1.20", "go1.20.0-bigcorp", 0},
 	{"go1.20rc1", "go1.20", -1},
 	{"go1.21", "go1.21.0", -1},
+	{"go1.21", "go1.21.0-bigcorp", -1},
 	{"go1.21", "go1.21rc1", -1},
 	{"go1.21rc1", "go1.21.0", -1},
 	{"go1.6", "go1.19", -1},
 	{"go1.19", "go1.19.1", -1},
 	{"go1.19rc1", "go1.19", -1},
+	{"go1.19rc1", "go1.19", -1},
 	{"go1.19rc1", "go1.19.1", -1},
 	{"go1.19rc1", "go1.19rc2", -1},
 	{"go1.19.0", "go1.19.1", -1},