diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index ee2a7a10..44438cbb 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -47,7 +47,7 @@ rubocop:
   before_script:
   - "apk add go-task"
   script:
-  - "git diff --name-status ${CI_MERGE_REQUEST_DIFF_BASE_SHA}...HEAD | grep -v \"^D\" | cut -f 2 | grep \"\.rb$\" | xargs go-task bundle -- exec rubocop"
+  - "./bin/modified_files | grep \"\.rb$$\" | xargs go-task bundle -- exec rubocop"
 haml:
   stage: "lint"
   rules:
@@ -55,4 +55,4 @@ haml:
   before_script:
   - "apk add go-task"
   script:
-  - "git diff --name-status ${CI_MERGE_REQUEST_DIFF_BASE_SHA}...HEAD | grep -v \"^D\" | cut -f 2 | grep \"\.haml$\" | xargs go-task bundle -- exec haml-lint"
+  - "./bin/modified_files | grep \"\.haml$$\" | xargs go-task bundle -- exec haml-lint"
diff --git a/bin/modified_files b/bin/modified_files
new file mode 100755
index 00000000..0e6a4e08
--- /dev/null
+++ b/bin/modified_files
@@ -0,0 +1,8 @@
+#!/bin/sh
+set -e
+
+test -n "${CI_MERGE_REQUEST_DIFF_BASE_SHA}"
+
+git diff --name-status ${CI_MERGE_REQUEST_DIFF_BASE_SHA}...rails \
+  | grep -v "^D" \
+  | cut -f 2