diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 60097e9e..6f7483a3 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -17,6 +17,8 @@ jobs:
         uses: actions/checkout@v2
         with:
           fetch-depth: 0
+      - name: shellcheck
+        uses: reviewdog/action-shellcheck@v1
       - name: Run changed-files with defaults
         id: changed-files
         uses: ./
diff --git a/action.yml b/action.yml
index ab22405d..020ffd86 100644
--- a/action.yml
+++ b/action.yml
@@ -54,99 +54,11 @@ runs:
   steps:
     - id: changed_files
       run: |
-        echo "Getting head sha..."
-
-        if [[ -z $GITHUB_BASE_REF ]]; then
-          HEAD_SHA=$(git rev-parse HEAD^1 || true)
-        else
-          TARGET_BRANCH=${GITHUB_BASE_REF}
-          git fetch --depth=1 origin ${TARGET_BRANCH}:${TARGET_BRANCH}
-          HEAD_SHA=$(git rev-parse ${TARGET_BRANCH} || true)
-        fi
-        
-        INPUT_FILES="${{ inputs.files }}"
-
-        if [[ -z "$INPUT_FILES" ]]; then
-
-          echo "Getting diff..."
-
-          ADDED=$(git diff --diff-filter=A --name-only "$HEAD_SHA" | tr "\n" "${{ inputs.separator }}" | sed -E 's/(${{ inputs.separator }})$//')
-          COPIED=$(git diff --diff-filter=C --name-only "$HEAD_SHA" | tr "\n" "${{ inputs.separator }}" | sed -E 's/(${{ inputs.separator }})$//')
-          DELETED=$(git diff --diff-filter=D --name-only "$HEAD_SHA" | tr "\n" "${{ inputs.separator }}" | sed -E 's/(${{ inputs.separator }})$//')
-          MODIFIED=$(git diff --diff-filter=M --name-only "$HEAD_SHA" | tr "\n" "${{ inputs.separator }}" | sed -E 's/(${{ inputs.separator }})$//')
-          RENAMED=$(git diff --diff-filter=R --name-only "$HEAD_SHA" | tr "\n" "${{ inputs.separator }}" | sed -E 's/(${{ inputs.separator }})$//')
-          CHANGED=$(git diff --diff-filter=T --name-only "$HEAD_SHA" | tr "\n" "${{ inputs.separator }}" | sed -E 's/(${{ inputs.separator }})$//')
-          UNMERGED=$(git diff --diff-filter=U --name-only "$HEAD_SHA" | tr "\n" "${{ inputs.separator }}" | sed -E 's/(${{ inputs.separator }})$//')
-          UNKNOWN=$(git diff --diff-filter=X --name-only "$HEAD_SHA" | tr "\n" "${{ inputs.separator }}" | sed -E 's/(${{ inputs.separator }})$//')
-          ALL_CHANGED=$(git diff --diff-filter='*ACDMRTUX' --name-only "$HEAD_SHA" | tr "\n" "${{ inputs.separator }}" | sed -E 's/(${{ inputs.separator }})$//')
-          ALL_MODIFIED_FILES=$(git diff --diff-filter='ACM' --name-only "$HEAD_SHA" | tr "\n" "${{ inputs.separator }}" | sed -E 's/(${{ inputs.separator }})$//')
-        else
-          ADDED=()
-          COPIED=()
-          DELETED=()
-          MODIFIED=()
-          RENAMED=()
-          CHANGED=()
-          UNMERGED=()
-          UNKNOWN=()
-          ALL_CHANGED=()
-          ALL_MODIFIED_FILES=()
-
-          for path in ${INPUT_FILES}
-          do
-            echo "Checking for file changes: \"${path}\"..."
-            ADDED+=$(git diff --diff-filter=A --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s${{ inputs.separator }}" || true)
-            COPIED+=$(git diff --diff-filter=C --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s${{ inputs.separator }}" || true)
-            DELETED+=$(git diff --diff-filter=D --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s${{ inputs.separator }}" || true)
-            MODIFIED+=$(git diff --diff-filter=M --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s${{ inputs.separator }}" || true)
-            RENAMED+=$(git diff --diff-filter=R --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s${{ inputs.separator }}" || true)
-            CHANGED+=$(git diff --diff-filter=T --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s${{ inputs.separator }}" || true)
-            UNMERGED+=$(git diff --diff-filter=U --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s${{ inputs.separator }}" || true)
-            UNKNOWN+=$(git diff --diff-filter=X --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s${{ inputs.separator }}" || true)
-            ALL_CHANGED+=$(git diff --diff-filter='*ACDMRTUX' --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s${{ inputs.separator }}" || true)
-            ALL_MODIFIED_FILES+=$(git diff --diff-filter='ACM' --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s${{ inputs.separator }}" || true)
-          done
-
-          ADDED=$(echo "$ADDED" | sed -E 's/(${{ inputs.separator }})$//')
-          COPIED=$(echo $COPIED | sed -E 's/(${{ inputs.separator }})$//')
-          DELETED=$(echo "$DELETED" | sed -E 's/(${{ inputs.separator }})$//')
-          MODIFIED=$(echo "$MODIFIED" | sed -E 's/(${{ inputs.separator }})$//')
-          RENAMED=$(echo "$RENAMED" | sed -E 's/(${{ inputs.separator }})$//')
-          CHANGED=$(echo "$CHANGED" | sed -E 's/(${{ inputs.separator }})$//')
-          UNMERGED=$(echo "$UNMERGED" | sed -E 's/(${{ inputs.separator }})$//')
-          UNKNOWN=$(echo "$UNKNOWN" | sed -E 's/(${{ inputs.separator }})$//')
-          ALL_CHANGED=$(echo "$ALL_CHANGED" | sed -E 's/(${{ inputs.separator }})$//')
-          ALL_MODIFIED_FILES=$(echo "$ALL_MODIFIED_FILES" | sed -E 's/(${{ inputs.separator }})$//')
-          
-          OUTPUT_ALL_MODIFIED_FILES=$(echo $ALL_MODIFIED_FILES | sed "s/${{ inputs.separator }}/ /g")
-          ALL_INPUT_FILES=$(echo $INPUT_FILES | sed "s/\n/ /g")
-
-          IFS=$' ' SORTED_INPUT_FILES=($(sort <<<"${ALL_INPUT_FILES[*]}"))
-          IFS=$' ' SORTED_OUTPUT_ALL_MODIFIED_FILES=($(sort <<<"${OUTPUT_ALL_MODIFIED_FILES[*]}"))
-          
-          if [[ "${SORTED_INPUT_FILES[*]}" == "${SORTED_OUTPUT_ALL_MODIFIED_FILES[*]}" ]]; then
-            echo "::set-output name=all_changed::true"
-          else
-            echo "::set-output name=all_changed::false"
-          fi
-
-          if [[ ${#SORTED_OUTPUT_ALL_MODIFIED_FILES[@]} -gt 0 ]]; then
-            echo "::set-output name=any_changed::true"
-          else
-            echo "::set-output name=any_changed::false"
-          fi
-        fi
-
-        echo "::set-output name=added_files::$ADDED"
-        echo "::set-output name=copied_files::$COPIED"
-        echo "::set-output name=deleted_files::$DELETED"
-        echo "::set-output name=modified_files::$MODIFIED"
-        echo "::set-output name=renamed_files::$RENAMED"
-        echo "::set-output name=changed_files::$CHANGED"
-        echo "::set-output name=unmerged_files::$UNMERGED"
-        echo "::set-output name=unknown_files::$UNKNOWN"
-        echo "::set-output name=all_changed_files::$ALL_CHANGED"
-        echo "::set-output name=all_modified_files::$ALL_MODIFIED_FILES"
+        export INPUT_FILES="${{ inputs.files }}"
+        export INPUT_SEPARATOR="${{ inputs.separator }}"
+        bash entrypoint.sh
+        unset INPUT_FILES
+        unset INPUT_SEPARATOR
       shell: bash
 
 branding:
diff --git a/entrypoint.sh b/entrypoint.sh
new file mode 100644
index 00000000..10aba224
--- /dev/null
+++ b/entrypoint.sh
@@ -0,0 +1,96 @@
+#!/usr/bin/env bash
+
+set -e
+
+echo "Getting head sha..."
+if [[ -z $GITHUB_BASE_REF ]]; then
+  HEAD_SHA=$(git rev-parse HEAD^1 || true)
+else
+  TARGET_BRANCH=${GITHUB_BASE_REF}
+  git fetch --depth=1 origin "${TARGET_BRANCH}":"${TARGET_BRANCH}"
+  HEAD_SHA=$(git rev-parse "${TARGET_BRANCH}" || true)
+fi
+
+if [[ -z "$INPUT_FILES" ]]; then
+  echo "Getting diff..."
+  ADDED=$(git diff --diff-filter=A --name-only "$HEAD_SHA" | tr "\n" "$INPUT_SEPARATOR" | sed -E "s/($INPUT_SEPARATOR)$//")
+  COPIED=$(git diff --diff-filter=C --name-only "$HEAD_SHA" | tr "\n" "$INPUT_SEPARATOR" | sed -E "s/($INPUT_SEPARATOR)$//")
+  DELETED=$(git diff --diff-filter=D --name-only "$HEAD_SHA" | tr "\n" "$INPUT_SEPARATOR" | sed -E "s/($INPUT_SEPARATOR)$//")
+  MODIFIED=$(git diff --diff-filter=M --name-only "$HEAD_SHA" | tr "\n" "$INPUT_SEPARATOR" | sed -E "s/($INPUT_SEPARATOR)$//")
+  RENAMED=$(git diff --diff-filter=R --name-only "$HEAD_SHA" | tr "\n" "$INPUT_SEPARATOR" | sed -E "s/($INPUT_SEPARATOR)$//")
+  CHANGED=$(git diff --diff-filter=T --name-only "$HEAD_SHA" | tr "\n" "$INPUT_SEPARATOR" | sed -E "s/($INPUT_SEPARATOR)$//")
+  UNMERGED=$(git diff --diff-filter=U --name-only "$HEAD_SHA" | tr "\n" "$INPUT_SEPARATOR" | sed -E "s/($INPUT_SEPARATOR)$//")
+  UNKNOWN=$(git diff --diff-filter=X --name-only "$HEAD_SHA" | tr "\n" "$INPUT_SEPARATOR" | sed -E "s/($INPUT_SEPARATOR)$//")
+  ALL_CHANGED=$(git diff --diff-filter="*ACDMRTUX" --name-only "$HEAD_SHA" | tr "\n" "$INPUT_SEPARATOR" | sed -E "s/($INPUT_SEPARATOR)$//")
+  ALL_MODIFIED_FILES=$(git diff --diff-filter="ACM" --name-only "$HEAD_SHA" | tr "\n" "$INPUT_SEPARATOR" | sed -E "s/($INPUT_SEPARATOR)$//")
+else
+  ADDED_ARRAY=()
+  COPIED_ARRAY=()
+  DELETED_ARRAY=()
+  MODIFIED_ARRAY=()
+  RENAMED_ARRAY=()
+  CHANGED_ARRAY=()
+  UNMERGED_ARRAY=()
+  UNKNOWN_ARRAY=()
+  ALL_CHANGED_ARRAY=()
+  ALL_MODIFIED_FILES_ARRAY=()
+
+  for path in ${INPUT_FILES}
+  do
+    echo "Checking for file changes: \"${path}\"..."
+    IFS=" " read -r -a ADDED_ARRAY <<< "$(git diff --diff-filter=A --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s$INPUT_SEPARATOR" || true)"
+    IFS=" " read -r -a COPIED_ARRAY <<< "$(git diff --diff-filter=C --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s$INPUT_SEPARATOR" || true)"
+    IFS=" " read -r -a DELETED_ARRAY <<< "$(git diff --diff-filter=D --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s$INPUT_SEPARATOR" || true)"
+    IFS=" " read -r -a MODIFIED_ARRAY <<< "$(git diff --diff-filter=M --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s$INPUT_SEPARATOR" || true)"
+    IFS=" " read -r -a RENAMED_ARRAY <<< "$(git diff --diff-filter=R --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s$INPUT_SEPARATOR" || true)"
+    IFS=" " read -r -a CHANGED_ARRAY <<< "$(git diff --diff-filter=T --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s$INPUT_SEPARATOR" || true)"
+    IFS=" " read -r -a UNMERGED_ARRAY <<< "$(git diff --diff-filter=U --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s$INPUT_SEPARATOR" || true)"
+    IFS=" " read -r -a UNKNOWN_ARRAY <<< "$(git diff --diff-filter=X --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s$INPUT_SEPARATOR" || true)"
+    IFS=" " read -r -a ALL_CHANGED_ARRAY <<< "$(git diff --diff-filter="*ACDMRTUX" --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s$INPUT_SEPARATOR" || true)"
+    IFS=" " read -r -a ALL_MODIFIED_FILES_ARRAY <<< "$(git diff --diff-filter="ACM" --name-only "$HEAD_SHA" | grep -E "(${path})" | xargs printf "%s$INPUT_SEPARATOR" || true)"
+  done
+
+  ADDED=$(echo "${ADDED_ARRAY[@]}" | sed -E "s/($INPUT_SEPARATOR)$//")
+  COPIED=$(echo "${COPIED_ARRAY[@]}" | sed -E "s/($INPUT_SEPARATOR)$//")
+  DELETED=$(echo "${DELETED_ARRAY[@]}" | sed -E "s/($INPUT_SEPARATOR)$//")
+  MODIFIED=$(echo "${MODIFIED_ARRAY[@]}" | sed -E "s/($INPUT_SEPARATOR)$//")
+  RENAMED=$(echo "${RENAMED_ARRAY[@]}" | sed -E "s/($INPUT_SEPARATOR)$//")
+  CHANGED=$(echo "${CHANGED_ARRAY[@]}" | sed -E "s/($INPUT_SEPARATOR)$//")
+  UNMERGED=$(echo "${UNMERGED_ARRAY[@]}" | sed -E "s/($INPUT_SEPARATOR)$//")
+  UNKNOWN=$(echo "${UNKNOWN_ARRAY[@]}" | sed -E "s/($INPUT_SEPARATOR)$//")
+  ALL_CHANGED=$(echo "${ALL_CHANGED_ARRAY[@]}" | sed -E "s/($INPUT_SEPARATOR)$//")
+  ALL_MODIFIED_FILES=$(echo "${ALL_MODIFIED_FILES_ARRAY[@]}" | sed -E "s/($INPUT_SEPARATOR)$//")
+
+  # shellcheck disable=SC2001
+  OUTPUT_ALL_MODIFIED_FILES=$(echo "$ALL_MODIFIED_FILES" | sed "s/$INPUT_SEPARATOR/ /g")
+  ALL_INPUT_FILES=${INPUT_FILES//\n/ }
+
+  SORTED_INPUT_FILES=()
+  SORTED_OUTPUT_ALL_MODIFIED_FILES=()
+
+  IFS=" " read -r -a SORTED_INPUT_FILES <<< "$(sort <<<"${ALL_INPUT_FILES[*]}")"
+  IFS=" " read -r -a SORTED_OUTPUT_ALL_MODIFIED_FILES <<< "$(sort <<<"${OUTPUT_ALL_MODIFIED_FILES[*]}")"
+
+  if [[ "${SORTED_INPUT_FILES[*]}" == "${SORTED_OUTPUT_ALL_MODIFIED_FILES[*]}" ]]; then
+    echo "::set-output name=all_changed::true"
+  else
+    echo "::set-output name=all_changed::false"
+  fi
+
+  if [[ ${#SORTED_OUTPUT_ALL_MODIFIED_FILES[@]} -gt 0 ]]; then
+    echo "::set-output name=any_changed::true"
+  else
+    echo "::set-output name=any_changed::false"
+  fi
+fi
+
+echo "::set-output name=added_files::$ADDED"
+echo "::set-output name=copied_files::$COPIED"
+echo "::set-output name=deleted_files::$DELETED"
+echo "::set-output name=modified_files::$MODIFIED"
+echo "::set-output name=renamed_files::$RENAMED"
+echo "::set-output name=changed_files::$CHANGED"
+echo "::set-output name=unmerged_files::$UNMERGED"
+echo "::set-output name=unknown_files::$UNKNOWN"
+echo "::set-output name=all_changed_files::$ALL_CHANGED"
+echo "::set-output name=all_modified_files::$ALL_MODIFIED_FILES"