diff --git a/.github/workflows/shellcheck.yml b/.github/workflows/shellcheck.yml
new file mode 100644
index 0000000..df37c68
--- /dev/null
+++ b/.github/workflows/shellcheck.yml
@@ -0,0 +1,15 @@
+on:
+  pull_request:
+
+name: "ShellCheck"
+
+jobs:
+  shellcheck:
+    name: Shellcheck
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Run ShellCheck
+        uses: ludeeus/action-shellcheck@master
+        env:
+          SHELLCHECK_OPTS: -e SC2154
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 03d5018..8ba38e3 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -8,7 +8,12 @@ repos:
         exclude: ^examples/
       - id: terraform_docs
         exclude: ^examples/
+
   - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v3.4.0
     hooks:
       - id: check-merge-conflict
+  - repo: https://github.com/koalaman/shellcheck-precommit
+    rev: v0.7.2
+    hooks:
+      - id: shellcheck
diff --git a/README.md b/README.md
index 4da8ed5..a5a553c 100644
--- a/README.md
+++ b/README.md
@@ -45,14 +45,14 @@ You can check the status of the certificate in the Google Cloud Console.
 
 | Name | Version |
 |------|---------|
-| <a name="requirement_terraform"></a> [terraform](#requirement\_terraform) | >= 1.2.0 |
+| <a name="requirement_terraform"></a> [terraform](#requirement\_terraform) | >= 0.13.0 |
 | <a name="requirement_google"></a> [google](#requirement\_google) | >=4.47.0 |
 
 ## Providers
 
 | Name | Version |
 |------|---------|
-| <a name="provider_google"></a> [google](#provider\_google) | 4.47.0 |
+| <a name="provider_google"></a> [google](#provider\_google) | >=4.47.0 |
 
 ## Modules
 
diff --git a/main.tf b/main.tf
index 70b43bf..f62f323 100644
--- a/main.tf
+++ b/main.tf
@@ -1,7 +1,7 @@
 locals {
-  // The default port that Atlantis runs on is 4141.
+  # The default port that Atlantis runs on is 4141.
   atlantis_port = lookup(var.env_vars, "ATLANTIS_PORT", 4141)
-  // Atlantis its home directory is "/home/atlantis".
+  # Atlantis its home directory is "/home/atlantis".
   atlantis_data_dir = lookup(var.env_vars, "ATLANTIS_DATA_DIR", "/home/atlantis")
   port_name         = "atlantis"
 }
@@ -35,8 +35,8 @@ resource "google_compute_instance_template" "atlantis" {
   machine_type         = var.machine_type
   can_ip_forward       = false
 
-  // Using the below scheduling configuration,
-  // the managed instance group will recreate the Spot VM if Compute Engine stops them
+  # Using the below scheduling configuration,
+  # the managed instance group will recreate the Spot VM if Compute Engine stops them
   scheduling {
     automatic_restart           = var.spot_machine_enabled ? false : true
     preemptible                 = var.spot_machine_enabled ? true : false
@@ -45,7 +45,7 @@ resource "google_compute_instance_template" "atlantis" {
     instance_termination_action = var.spot_machine_enabled ? "STOP" : null
   }
 
-  // Ephemeral OS boot disk
+  # Ephemeral OS boot disk
   disk {
     source_image = data.google_compute_image.cos.self_link
     auto_delete  = true
@@ -61,7 +61,7 @@ resource "google_compute_instance_template" "atlantis" {
     }
   }
 
-  // Persistent disk for Atlantis
+  #  Persistent disk for Atlantis
   disk {
     device_name  = "atlantis-disk-0"
     disk_type    = "pd-ssd"
@@ -94,8 +94,8 @@ resource "google_compute_instance_template" "atlantis" {
 
   project = var.project
 
-  // Instance Templates cannot be updated after creation with the Google Cloud Platform API. 
-  // In order to update an Instance Template, Terraform will destroy the existing resource and create a replacement
+  # Instance Templates cannot be updated after creation with the Google Cloud Platform API. 
+  # In order to update an Instance Template, Terraform will destroy the existing resource and create a replacement
   lifecycle {
     create_before_destroy = true
   }
@@ -108,9 +108,9 @@ module "atlantis" {
   container = {
     image = var.image
     securityContext = {
-      privileged : true
+      privileged = true
     }
-    tty : true
+    tty = true
     env = [for key, value in var.env_vars : {
       name  = key
       value = value
diff --git a/startup-script.sh b/startup-script.sh
index bd476b7..7a48b05 100644
--- a/startup-script.sh
+++ b/startup-script.sh
@@ -1,5 +1,8 @@
 #!/bin/bash
 
+# Exit immediately if a command returns a non-zero code
+set -e
+
 cat > /etc/systemd/system/atlantis-chown-disk.service <<EOF
 [Unit]
 Description=Chown the Atlantis mount
diff --git a/versions.tf b/versions.tf
index 813378e..f223a73 100644
--- a/versions.tf
+++ b/versions.tf
@@ -1,5 +1,5 @@
 terraform {
-  required_version = ">= 1.2.0"
+  required_version = ">= 0.13.0"
 
   required_providers {
     google = {