diff --git a/internal/rosa/gnu.go b/internal/rosa/gnu.go
index 91456c7..d8f9c8f 100644
--- a/internal/rosa/gnu.go
+++ b/internal/rosa/gnu.go
@@ -4,8 +4,8 @@ import "hakurei.app/internal/pkg"
 
 func (t Toolchain) newM4() (pkg.Artifact, string) {
 	const (
-		version  = "1.4.20"
-		checksum = "RT0_L3m4Co86bVBY3lCFAEs040yI1WdeNmRylFpah8IZovTm6O4wI7qiHJN3qsW9"
+		version  = "1.4.21"
+		checksum = "pPa6YOo722Jw80l1OsH1tnUaklnPFjFT-bxGw5iAVrZTm1P8FQaWao_NXop46-pm"
 	)
 	return t.NewPackage("m4", version, pkg.NewHTTPGetTar(
 		nil, "https://ftpmirror.gnu.org/gnu/m4/m4-"+version+".tar.bz2",
@@ -18,6 +18,8 @@ chmod +w tests/test-c32ispunct.sh && echo '#!/bin/sh' > tests/test-c32ispunct.sh
 `,
 	}, (*MakeHelper)(nil),
 		Diffutils,
+
+		KernelHeaders,
 	), version
 }
 func init() {