diff --git a/src/go/build/syslist.go b/src/go/build/syslist.go
index ea67662c3e..35cffce6dc 100644
--- a/src/go/build/syslist.go
+++ b/src/go/build/syslist.go
@@ -4,6 +4,10 @@
 
 package build
 
+// Note that this file is read by internal/goarch/gengoarch.go and by
+// internal/goos/gengoos.go. If you change this file, look at those
+// files as well.
+
 // knownOS is the list of past, present, and future known GOOS values.
 // Do not remove from this list, as it is used for filename matching.
 // If you add an entry to this list, look at unixOS, below.
diff --git a/src/internal/goarch/gengoarch.go b/src/internal/goarch/gengoarch.go
index 3c706e04ad..0b0be5cd15 100644
--- a/src/internal/goarch/gengoarch.go
+++ b/src/internal/goarch/gengoarch.go
@@ -11,7 +11,6 @@ import (
 	"fmt"
 	"log"
 	"os"
-	"strconv"
 	"strings"
 )
 
@@ -22,14 +21,18 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	const goarchPrefix = `const goarchList = `
+	const goarchPrefix = `var knownArch = map[string]bool{`
+	inGOARCH := false
 	for _, line := range strings.Split(string(data), "\n") {
 		if strings.HasPrefix(line, goarchPrefix) {
-			text, err := strconv.Unquote(strings.TrimPrefix(line, goarchPrefix))
-			if err != nil {
-				log.Fatalf("parsing goarchList: %v", err)
-			}
-			goarches = strings.Fields(text)
+			inGOARCH = true
+		} else if inGOARCH && strings.HasPrefix(line, "}") {
+			break
+		} else if inGOARCH {
+			goarch := strings.Fields(line)[0]
+			goarch = strings.TrimPrefix(goarch, `"`)
+			goarch = strings.TrimSuffix(goarch, `":`)
+			goarches = append(goarches, goarch)
 		}
 	}
 
@@ -39,7 +42,7 @@ func main() {
 		}
 		var buf bytes.Buffer
 		fmt.Fprintf(&buf, "// Code generated by gengoarch.go using 'go generate'. DO NOT EDIT.\n\n")
-		fmt.Fprintf(&buf, "//go:build %s\n", target) // must explicitly include target for bootstrapping purposes
+		fmt.Fprintf(&buf, "//go:build %s\n\n", target) // must explicitly include target for bootstrapping purposes
 		fmt.Fprintf(&buf, "package goarch\n\n")
 		fmt.Fprintf(&buf, "const GOARCH = `%s`\n\n", target)
 		for _, goarch := range goarches {
diff --git a/src/internal/goos/gengoos.go b/src/internal/goos/gengoos.go
index 1b62503fd0..37d9706d1e 100644
--- a/src/internal/goos/gengoos.go
+++ b/src/internal/goos/gengoos.go
@@ -11,7 +11,6 @@ import (
 	"fmt"
 	"log"
 	"os"
-	"strconv"
 	"strings"
 )
 
@@ -22,14 +21,18 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	const goosPrefix = `const goosList = `
+	const goosPrefix = `var knownOS = map[string]bool{`
+	inGOOS := false
 	for _, line := range strings.Split(string(data), "\n") {
 		if strings.HasPrefix(line, goosPrefix) {
-			text, err := strconv.Unquote(strings.TrimPrefix(line, goosPrefix))
-			if err != nil {
-				log.Fatalf("parsing goosList: %v", err)
-			}
-			gooses = strings.Fields(text)
+			inGOOS = true
+		} else if inGOOS && strings.HasPrefix(line, "}") {
+			break
+		} else if inGOOS {
+			goos := strings.Fields(line)[0]
+			goos = strings.TrimPrefix(goos, `"`)
+			goos = strings.TrimSuffix(goos, `":`)
+			gooses = append(gooses, goos)
 		}
 	}
 
@@ -50,7 +53,7 @@ func main() {
 		tags = append(tags, target) // must explicitly include target for bootstrapping purposes
 		var buf bytes.Buffer
 		fmt.Fprintf(&buf, "// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.\n\n")
-		fmt.Fprintf(&buf, "//go:build %s\n", strings.Join(tags, " && "))
+		fmt.Fprintf(&buf, "//go:build %s\n\n", strings.Join(tags, " && "))
 		fmt.Fprintf(&buf, "package goos\n\n")
 		fmt.Fprintf(&buf, "const GOOS = `%s`\n\n", target)
 		for _, goos := range gooses {