diff --git a/core/m4/checksums b/core/m4/checksums
index 00033add..1357398a 100644
--- a/core/m4/checksums
+++ b/core/m4/checksums
@@ -1 +1 @@
-ab2633921a5cd38e48797bf5521ad259bdc4b979078034a3b790d7fec5493fab  m4-1.4.18.tar.gz
+f2c1e86ca0a404ff281631bdc8377638992744b175afb806e25871a24a934e07  m4-1.4.18.tar.xz
diff --git a/core/m4/sources b/core/m4/sources
index fdbf54be..07be0f71 100644
--- a/core/m4/sources
+++ b/core/m4/sources
@@ -1 +1 @@
-ftp://ftp.gnu.org/gnu/m4/m4-1.4.18.tar.gz
+https://ftp.gnu.org/gnu/m4/m4-1.4.18.tar.xz