diff --git a/profiles/prefix/linux/package.mask b/profiles/prefix/linux/package.mask
index 34c6186b8bc1d..3b2f7125eace0 100644
--- a/profiles/prefix/linux/package.mask
+++ b/profiles/prefix/linux/package.mask
@@ -1,6 +1,12 @@
-# Copyright 1999-2019 Gentoo Authors
+# Copyright 1999-2025 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
+# Fabian Groffen <grobian@gentoo.org> (2025-12-22)
+# Fails to compile in gnulib on invalid decls for memset, memmove,
+# strncpy, etc. probably incompatibility with system headers
+# same as for macOS, not on RAP, so probably caused by libc (version)
+=sys-devel/m4-1.4.20
+
 # Michael Haubenwallner <haubi@gentoo.org> (2019-01-08)
 # Prefix Guest does use host libc and host kernel's headers,
 # hence packages should depend on virtual/os-headers instead.