diff --git a/.github/CONTRIBUTING.txt b/.github/CONTRIBUTING.txt
index cd13445a..3d183307 100644
--- a/.github/CONTRIBUTING.txt
+++ b/.github/CONTRIBUTING.txt
@@ -13,9 +13,16 @@ Here's the long and short of it:
 
       git clone git@github.com:your-username/scikit-image.git
 
-   * Add the upstream repository::
+   * Add the upstream repository:
 
-      git remote add upstream git@github.com:scikit-image/scikit-image.git
+     - If you have set up your `github SSH keys
+       <https://help.github.com/articles/adding-a-new-ssh-key-to-your-github-account/>`_::
+
+        git remote add upstream git@github.com:scikit-image/scikit-image.git
+
+     - Otherwise::
+
+        git remote add upstream https://github.com/scikit-image/scikit-image.git
 
    * Now, you have remote repositories named: