diff --git a/pills/02-install-on-your-running.xml b/pills/02-install-on-your-running.xml
index 538c4bb..16f167b 100644
--- a/pills/02-install-on-your-running.xml
+++ b/pills/02-install-on-your-running.xml
@@ -15,6 +15,9 @@
   <para>
     Now we'll install Nix on our running system and understand what
     changed in our system after the installation.
+    <emphasis role="bold">If you're using NixOS, Nix is already installed;
+    you can skip to the <link
+    linkend="install-on-your-running-system">next</link> pill.</emphasis>
   </para>
 
   <para>
@@ -66,7 +69,7 @@
 
     <para>
       That's the <filename>/nix/store</filename> we
-      were talking in the first article. We're copying in the 
+      were talking in the first article. We're copying in the
       necessary software to bootstrap a Nix system. You can see bash,
       coreutils, the C compiler toolchain, perl libraries, sqlite and Nix itself
       with its own tools and libnix.
@@ -133,7 +136,7 @@
 
     <para>
       A profile in Nix is a general and convenient concept for
-      realizing rollbacks. Profiles are used to compose 
+      realizing rollbacks. Profiles are used to compose
       components that are spread among multiple paths under a new
       unified path. Not only that, but profiles are made up of multiple
       "generations": they are versioned. Whenever you change a profile,
@@ -152,7 +155,7 @@
     <xi:include href="./02/profile.xml" parse="xml" />
     <para>
      That <package>nix-2.1.3</package> derivation in the Nix store is
-     Nix itself, with binaries and libraries. The process of "installing" 
+     Nix itself, with binaries and libraries. The process of "installing"
      the derivation in the profile basically reproduces the hierarchy of the
      <package>nix-2.1.3</package> store derivation in the profile by means of
      symbolic links.
@@ -239,7 +242,7 @@
       does is simply to add <filename>~/.nix-profile/bin</filename> to
       <varname>PATH</varname> and
       <filename>~/.nix-defexpr/channels/nixpkgs</filename> to
-      <varname>NIX_PATH</varname>. We'll discuss 
+      <varname>NIX_PATH</varname>. We'll discuss
       <varname>NIX_PATH</varname> later.
     </para>
 
diff --git a/pills/03-enter-environment.xml b/pills/03-enter-environment.xml
index 2aac0c2..4387bbd 100644
--- a/pills/03-enter-environment.xml
+++ b/pills/03-enter-environment.xml
@@ -16,6 +16,11 @@
   <section>
     <title>Enter the environment</title>
 
+    <para>
+      <emphasis role="bold">If you're using NixOS, you can skip to the <link
+      linkend="install-something">next</link> step.</emphasis>
+    </para>
+
     <para>
       In the previous article we created a Nix user, so let's start by switching
       to it with <command>su - nix</command>. If your
@@ -36,7 +41,7 @@
     </para>
   </section>
 
-  <section>
+  <section xml:id="install-something">
     <title>Install something</title>
 
     <para>
@@ -325,6 +330,12 @@
 
     <screen><xi:include href="./03/channel-list.txt" parse="text" /></screen>
 
+    <para>
+      If you're using NixOS, you may not see any output from the above command
+      (if you're using the default), or you may see a channel whose
+      name begins with "nixos-" instead of "nixpkgs".
+    </para>
+
     <para>
       That's essentially the contents of <filename>~/.nix-channels</filename>.
     </para>