diff --git a/apt.txt b/apt.txt
index a165697..bf7b028 100644
--- a/apt.txt
+++ b/apt.txt
@@ -1,3 +1,4 @@
+zsh
 tmux
 postgresql
 postgresql-contrib
diff --git a/bootstrap.sh b/bootstrap.sh
index 9c1dc14..0e93f51 100644
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -1,14 +1,5 @@
 #!/bin/bash
 
-# 1. PRECONDITIONS
-#
-# zsh is expected to be set up.
-
-if [ -z "$(zsh --version 2> /dev/null)" ]; then
-    echo "💥 Install zsh (https://www.zsh.org/) before installing environment."
-    return
-fi
-
 # Ensuring steps are defined.
 . ./steps.sh