diff --git a/README.md b/README.md
index b6df4c4..bdf05f7 100644
--- a/README.md
+++ b/README.md
@@ -1,56 +1,56 @@
 Software Heritage Python development environment
 ================================================
 
 This repository contains the scaffolding to initialize and keep a local
 development environment for the Software Heritage Python stack. In particular,
 it contains pointers to the Git repositories of all Software Heritage Python
 modules. The repositories are managed using [myrepos][1] (see the .mrconfig
 file), and the `mr` command.
 
 [1]: http://myrepos.branchable.com/
 
 In Debian, the "mr" command is shipped in the "mr" package.
 
-As our `.mrconfig` file contains "untrusted" checkout commands (specifically:
-ensuring pre-commit hooks exist where needed), you need to add the path of your
-`.mrconfig` file to your `~/.mrtrust` file:
+Once you have installed "mr", just use the following helper for both initial
+code checkout and subsequent updates:
 
-    readlink -f .mrconfig >> ~/.mrtrust
- 
-You can then checkout the repositories using `mr up`.
+    cd swh-environment
+    bin/update
 
-See `.mrconfig` for the actual list of repositories.
+Note that the first time you run `bin/update` it will add the
+`swh-environment/.mrconfig` file to your `~/.mrtrust` (we use this to be able
+to setup pre-commit hooks upon repository checkouts). See `MR(1)` for more
+information about trusted `mr` repositories.
 
-For periodic updates after initial setup, you can use the `bin/update` helper:
+You can also checkout/update repositories by hand using `mr up`.
 
-    cd swh-environment
-    bin/update
+See `.mrconfig` for the actual list of repositories.
 
 
 PYTHONPATH
 ----------
 
 We use several Python modules, that should all be in the PYTHONPATH to be
 found. To that extent, we provide in this repository a script to set the
 PYTHONPATH variable to the correct value. You can use it as follows:
 
     . pythonpath.sh
 
 
 Initialize a new Python package repository
 ------------------------------------------
 
 1. create the remote Git repository on the forge
 
 2. add it to `.mrconfig` (e.g. using mr register)
 
 3. mr update
 
    this will clone the (empty) repository locally
 
 4. bin/init-py-repo REPO_NAME
 
    this will fill the repository with the template for SWH Python packages, and
    make an initial commit
 
 5. cd REPO_NAME ; git push
diff --git a/bin/update b/bin/update
index 6c4b6a0..6db3664 100755
--- a/bin/update
+++ b/bin/update
@@ -1,3 +1,11 @@
 #!/bin/bash
+
+mrconf=$(readlink -f .mrconfig)
+mrtrust="${HOME}/.mrtrust"
+if ! grep -q "$mrconf" "$mrtrust" &> /dev/null ; then
+    echo "I: mr repository not found in ${mrtrust}, adding it."
+    echo "$mrconf" >> "$mrtrust"
+fi
+
 git pull
 mr -j 4 update