diff --git a/Justfile b/Justfile
index 5b66483..51314c2 100755
--- a/Justfile
+++ b/Justfile
@@ -1,9 +1,18 @@
 _DEFAULT_VERSION_TMPL:
 	echo "{{invocation_directory()}}/nix/variables/versions.tmpl.nix"
 
+_DEFAULT_VERSION:
+	echo "{{invocation_directory()}}/nix/variables/versions.nix"
+
 _usage:
 	just -l
 
+update-default-versions:
+	#!/usr/bin/env bash
+	template="$(just _DEFAULT_VERSION_TMPL)"
+	outfile="$(just _DEFAULT_VERSION)"
+	esh -o ${outfile} ${template}
+
 _get_nix_path versionsPath:
 	echo $(set -x; nix-build --no-link --show-trace {{invocation_directory()}}/nix/default.nix -A channelSources --argstr versionsPath  {{versionsPath}} --argstr rebuildarg "dummy")