diff --git a/contrib/guix/guix-build b/contrib/guix/guix-build
index 5ed3278b..198f2dd8 100755
--- a/contrib/guix/guix-build
+++ b/contrib/guix/guix-build
@@ -231,8 +231,7 @@ host_to_commonname() {
     esac
 }
 
-# Determine the reference time used for determinism (overridable by environment)
-SOURCE_DATE_EPOCH="${SOURCE_DATE_EPOCH:-$(git -c log.showSignature=false log --format=%at -1)}"
+SOURCE_DATE_EPOCH="1672070414"
 
 # Precious directories are those which should not be cleaned between successive
 # guix builds