diff --git a/src/go/build/build.go b/src/go/build/build.go
index dce0304ba48..baf76e6b7ff 100644
--- a/src/go/build/build.go
+++ b/src/go/build/build.go
@@ -1965,18 +1965,6 @@ func (ctxt *Context) goodOSArchFile(name string, allTags map[string]bool) bool {
 	return true
 }
 
-var knownOS = make(map[string]bool)
-var knownArch = make(map[string]bool)
-
-func init() {
-	for _, v := range strings.Fields(goosList) {
-		knownOS[v] = true
-	}
-	for _, v := range strings.Fields(goarchList) {
-		knownArch[v] = true
-	}
-}
-
 // ToolDir is the directory containing build tools.
 var ToolDir = getToolDir()
 
diff --git a/src/go/build/syslist.go b/src/go/build/syslist.go
index 0f6e3369253..6b62b63042b 100644
--- a/src/go/build/syslist.go
+++ b/src/go/build/syslist.go
@@ -4,8 +4,51 @@
 
 package build
 
-// List of past, present, and future known GOOS and GOARCH values.
+// Past, present, and future known GOOS and GOARCH values.
 // Do not remove from this list, as these are used for go/build filename matching.
 
-const goosList = "aix android darwin dragonfly freebsd hurd illumos ios js linux nacl netbsd openbsd plan9 solaris windows zos "
-const goarchList = "386 amd64 amd64p32 arm armbe arm64 arm64be loong64 mips mipsle mips64 mips64le mips64p32 mips64p32le ppc ppc64 ppc64le riscv riscv64 s390 s390x sparc sparc64 wasm "
+var knownOS = map[string]bool{
+	"aix":       true,
+	"android":   true,
+	"darwin":    true,
+	"dragonfly": true,
+	"freebsd":   true,
+	"hurd":      true,
+	"illumos":   true,
+	"ios":       true,
+	"js":        true,
+	"linux":     true,
+	"nacl":      true,
+	"netbsd":    true,
+	"openbsd":   true,
+	"plan9":     true,
+	"solaris":   true,
+	"windows":   true,
+	"zos":       true,
+}
+var knownArch = map[string]bool{
+	"386":         true,
+	"amd64":       true,
+	"amd64p32":    true,
+	"arm":         true,
+	"armbe":       true,
+	"arm64":       true,
+	"arm64be":     true,
+	"loong64":     true,
+	"mips":        true,
+	"mipsle":      true,
+	"mips64":      true,
+	"mips64le":    true,
+	"mips64p32":   true,
+	"mips64p32le": true,
+	"ppc":         true,
+	"ppc64":       true,
+	"ppc64le":     true,
+	"riscv":       true,
+	"riscv64":     true,
+	"s390":        true,
+	"s390x":       true,
+	"sparc":       true,
+	"sparc64":     true,
+	"wasm":        true,
+}