diff --git a/default.nix b/default.nix
index 0573eaeb11ebc868455651e0b06e1e78b9cb2f4b..7245206b6206ce9054f035e2799dd0e4d52b8098 100644
--- a/default.nix
+++ b/default.nix
@@ -1,10 +1,13 @@
 {
-  argopkgs-src ? (builtins.fetchGit {
-    url = https://xgitlab.cels.anl.gov/argo/argopkgs.git;
-    ref = "master";
-    rev = "86c53fa5ba67edb3994f6ed971cdfa14bf850b4b";
-  }) ,
-  pkgs ? (import argopkgs-src {}),
+  argopkgs-src ?
+   let
+      hostPkgs = import <nixpkgs> {};
+      pinnedVersion = hostPkgs.lib.importJSON ./pin.json;
+    in
+      hostPkgs.fetchgit {
+        inherit (pinnedVersion) url rev sha256;
+      },
+  pkgs ? import argopkgs-src {},
   nrm-src ? pkgs.nodelevel.nrm.src,
   containers-src ? pkgs.nodelevel.containers.src,
   libnrm-src ? pkgs.nodelevel.libnrm.src
diff --git a/pin.json b/pin.json
new file mode 100644
index 0000000000000000000000000000000000000000..2565c5b2dc75bf0e4b5199301218e6f79144cc9d
--- /dev/null
+++ b/pin.json
@@ -0,0 +1,7 @@
+{
+  "url": "https://xgitlab.cels.anl.gov/argo/argopkgs.git",
+  "rev": "61beb966b287b9fbc08b977d2825d54ad161dd85",
+  "date": "2018-12-21T12:26:45-06:00",
+  "sha256": "0l32pd2viwqj78596v5393s9bhldpykgvb6gsg59i9qr1913x6f6",
+  "fetchSubmodules": true
+}
diff --git a/pin.sh b/pin.sh
new file mode 100755
index 0000000000000000000000000000000000000000..6d58e788403893d024732e8f52e2a6d5ab6f4e0a
--- /dev/null
+++ b/pin.sh
@@ -0,0 +1,2 @@
+#! /usr/bin/env sh
+nix-prefetch-git https://xgitlab.cels.anl.gov/argo/argopkgs.git refs/heads/master > pin.json