diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 488135c8..eaac4a7d 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -119,6 +119,34 @@ jobs:
         shell:
           bash
 
+  test-unset-github-output-env:
+    name: Test unset GITHUB_OUTPUT env
+    runs-on: ${{ matrix.platform }}
+    strategy:
+      fail-fast: false
+      max-parallel: 4
+      matrix:
+        platform: [ubuntu-latest, ubuntu-22.04, windows-latest, macos-latest, macos-11, ubuntu-18.04, windows-2022]
+
+    steps:
+      - name: Checkout to branch
+        uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+
+      - name: Run changed-files with unset GITHUB_OUTPUT env
+        id: changed-files
+        continue-on-error: true
+        uses: ./
+        env:
+          GITHUB_OUTPUT: ""
+
+      - name: Show output
+        run: |
+          echo '${{ toJSON(steps.changed-files.outputs) }}'
+        shell:
+          bash
+
   test-single-commit-history:
     name: Test changed-files single commit history
     runs-on: ${{ matrix.platform }}
@@ -335,6 +363,7 @@ jobs:
         continue-on-error: true
         with:
           since: "2022-08-19"
+          target_branch_fetch_depth: "20000"
       - name: Show output
         run: |
           echo '${{ toJSON(steps.changed-files-since.outputs) }}'
@@ -346,6 +375,7 @@ jobs:
         continue-on-error: true
         with:
           until: "2022-08-20"
+          target_branch_fetch_depth: "20000"
       - name: Show output
         run: |
           echo '${{ toJSON(steps.changed-files-until.outputs) }}'
diff --git a/action.yml b/action.yml
index 0501b614..9c47d21d 100644
--- a/action.yml
+++ b/action.yml
@@ -150,33 +150,6 @@ outputs:
 runs:
   using: "composite"
   steps:
-    - run: |
-        # "Calculate the base sha..."
-        bash $GITHUB_ACTION_PATH/get-base-sha.sh
-      id: base-sha
-      shell: bash
-      env:
-        GITHUB_WORKSPACE: ${{ github.workspace }}
-        GITHUB_EVENT_BEFORE: ${{ github.event.before }}
-        GITHUB_EVENT_FORCED : ${{ github.event.forced }}
-        # INPUT_<VARIABLE_NAME> is not available in Composite run steps
-        # https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#example-specifying-inputs
-        INPUT_SINCE: ${{ inputs.since }}
-        INPUT_BASE_SHA: ${{ inputs.base_sha }}
-        INPUT_SHA: ${{ inputs.sha }}
-        INPUT_PATH: ${{ inputs.path }}
-    - run: |
-        # "Calculate the sha..."
-        bash $GITHUB_ACTION_PATH/get-sha.sh
-      id: sha
-      shell: bash
-      env:
-        GITHUB_WORKSPACE: ${{ github.workspace }}
-        # INPUT_<VARIABLE_NAME> is not available in Composite run steps
-        # https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#example-specifying-inputs
-        INPUT_UNTIL: ${{ inputs.until }}
-        INPUT_SHA: ${{ inputs.sha }}
-        INPUT_PATH: ${{ inputs.path }}
     - run: |
         # "Calculating the previous and current SHA..."
         bash $GITHUB_ACTION_PATH/diff-sha.sh
@@ -193,8 +166,10 @@ runs:
         GITHUB_EVENT_FORCED: ${{ github.event.forced }}
         # INPUT_<VARIABLE_NAME> is not available in Composite run steps
         # https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#example-specifying-inputs
-        INPUT_SHA: ${{ steps.sha.outputs.sha }}
-        INPUT_BASE_SHA: ${{ steps.base-sha.outputs.base_sha }}
+        INPUT_SHA: ${{ inputs.sha }}
+        INPUT_BASE_SHA: ${{ inputs.base_sha }}
+        INPUT_SINCE: ${{ inputs.since }}
+        INPUT_UNTIL: ${{ inputs.until }}
         INPUT_PATH: ${{ inputs.path }}
         INPUT_TARGET_BRANCH_FETCH_DEPTH: ${{ inputs.target_branch_fetch_depth }}
     - name: Glob match
diff --git a/diff-sha.sh b/diff-sha.sh
index f6157dde..f7831edb 100644
--- a/diff-sha.sh
+++ b/diff-sha.sh
@@ -3,6 +3,7 @@
 set -eu
 
 INITIAL_COMMIT="false"
+GITHUB_OUTPUT=${GITHUB_OUTPUT:-""}
 
 echo "::group::changed-files-diff-sha"
 
@@ -40,7 +41,16 @@ fi
 echo "::debug::Getting HEAD SHA..."
 
 if [[ -z $INPUT_SHA ]]; then
-  CURRENT_SHA=$(git rev-list -n 1 "HEAD" 2>&1) && exit_status=$? || exit_status=$?
+  if [[ -n "$INPUT_UNTIL" ]]; then
+    CURRENT_SHA=$(git log -1 --format="%H" --date=local --until="$INPUT_UNTIL") && exit_status=$? || exit_status=$?
+
+    if [[ $exit_status -ne 0 ]]; then
+      echo "::error::Invalid until date: $INPUT_UNTIL"
+      exit 1
+    fi
+  else
+    CURRENT_SHA=$(git rev-list -n 1 "HEAD" 2>&1) && exit_status=$? || exit_status=$?
+  fi
 else
   CURRENT_SHA=$INPUT_SHA; exit_status=$?
 fi
@@ -63,22 +73,37 @@ if [[ -z $GITHUB_BASE_REF ]]; then
 
   if [[ -z $INPUT_BASE_SHA ]]; then
     git fetch --no-tags -u --progress origin --depth="$INPUT_TARGET_BRANCH_FETCH_DEPTH" "${TARGET_BRANCH}":"${TARGET_BRANCH}" && exit_status=$? || exit_status=$?
-    PREVIOUS_SHA=""
 
-    if [[ "$GITHUB_EVENT_FORCED" == "false" ]]; then
-      PREVIOUS_SHA=$GITHUB_EVENT_BEFORE
-    fi
+    if [[ -n "$INPUT_SINCE" ]]; then
+      PREVIOUS_SHA=$(git log --format="%H" --date=local --since="$INPUT_SINCE" --reverse | head -n 1)
 
-    if [[ -z "$PREVIOUS_SHA" || "$PREVIOUS_SHA" == "0000000000000000000000000000000000000000" ]]; then
-      PREVIOUS_SHA=$(git rev-parse "$(git branch -r --sort=-committerdate | head -1 | xargs)")
-    fi
+      if [[ -z "$PREVIOUS_SHA" ]]; then
+        echo "::error::Unable to locate a previous commit for the specified date: $INPUT_SINCE"
+        exit 1
+      fi
+    else
+      PREVIOUS_SHA=""
 
-    if [[ "$PREVIOUS_SHA" == "$CURRENT_SHA" ]]; then
-      PREVIOUS_SHA=$(git rev-parse "$CURRENT_SHA^1")
+      if [[ "$GITHUB_EVENT_FORCED" == "false" ]]; then
+        PREVIOUS_SHA=$GITHUB_EVENT_BEFORE
+      fi
+
+      if [[ -z "$PREVIOUS_SHA" || "$PREVIOUS_SHA" == "0000000000000000000000000000000000000000" ]]; then
+        PREVIOUS_SHA=$(git rev-parse "$(git branch -r --sort=-committerdate | head -1 | xargs)")
+      fi
 
       if [[ "$PREVIOUS_SHA" == "$CURRENT_SHA" ]]; then
-        INITIAL_COMMIT="true"
-        echo "::debug::Initial commit detected"
+        PREVIOUS_SHA=$(git rev-parse "$CURRENT_SHA^1")
+
+        if [[ "$PREVIOUS_SHA" == "$CURRENT_SHA" ]]; then
+          INITIAL_COMMIT="true"
+          echo "::debug::Initial commit detected"
+        fi
+      fi
+
+      if [[ -z "$PREVIOUS_SHA" ]]; then
+        echo "::error::Unable to locate a previous commit"
+        exit 1
       fi
     fi
   else
@@ -132,11 +157,18 @@ if [[ -n "$PREVIOUS_SHA" && -n "$CURRENT_SHA" && "$PREVIOUS_SHA" == "$CURRENT_SH
   exit 1
 fi
 
-cat <<EOF >> "$GITHUB_OUTPUT"
+if [[ -z "$GITHUB_OUTPUT" ]]; then
+  echo "::set-output name=target_branch::$TARGET_BRANCH"
+  echo "::set-output name=current_branch::$CURRENT_BRANCH"
+  echo "::set-output name=previous_sha::$PREVIOUS_SHA"
+  echo "::set-output name=current_sha::$CURRENT_SHA"
+else
+  cat <<EOF >> "$GITHUB_OUTPUT"
 target_branch=$TARGET_BRANCH
 current_branch=$CURRENT_BRANCH
 previous_sha=$PREVIOUS_SHA
 current_sha=$CURRENT_SHA
 EOF
+fi
 
 echo "::endgroup::"
diff --git a/get-base-sha.sh b/get-base-sha.sh
deleted file mode 100644
index 09e8703c..00000000
--- a/get-base-sha.sh
+++ /dev/null
@@ -1,24 +0,0 @@
-#!/usr/bin/env bash
-
-set -eu
-
-if [[ -n $INPUT_PATH ]]; then
-  REPO_DIR="$GITHUB_WORKSPACE/$INPUT_PATH"
-
-  echo "Resolving repository path: $REPO_DIR"
-  if [[ ! -d "$REPO_DIR" ]]; then
-    echo "::error::Invalid repository path: $REPO_DIR"
-    exit 1
-  fi
-  cd "$REPO_DIR"
-fi
-
-if [[ -n "$INPUT_SINCE" ]]; then
-  BASE_SHA=$(git log --format="%H" --date=local --since="$INPUT_SINCE" --reverse | head -n 1)
-  if [[ -z "$BASE_SHA" ]]; then
-    echo "::warning::The BASE_SHA for date '$INPUT_SINCE' couldn't be determined."
-  fi
-  echo "base_sha=$BASE_SHA" >> "$GITHUB_OUTPUT"
-elif [[ -n "$INPUT_BASE_SHA" ]]; then
-  echo "base_sha=$INPUT_BASE_SHA" >> "$GITHUB_OUTPUT"
-fi
diff --git a/get-changed-paths.sh b/get-changed-paths.sh
index 388474ce..e597d256 100755
--- a/get-changed-paths.sh
+++ b/get-changed-paths.sh
@@ -7,6 +7,8 @@ INPUT_SEPARATOR="${INPUT_SEPARATOR//'.'/'%2E'}"
 INPUT_SEPARATOR="${INPUT_SEPARATOR//$'\n'/'%0A'}"
 INPUT_SEPARATOR="${INPUT_SEPARATOR//$'\r'/'%0D'}"
 
+GITHUB_OUTPUT=${GITHUB_OUTPUT:-""}
+
 if [[ $INPUT_QUOTEPATH == "false" ]]; then
   git config --global core.quotepath off
 else
@@ -131,9 +133,17 @@ else
 
   if [[ -n "${ALL_CHANGED}" ]]; then
     echo "::debug::Matching changed files: ${ALL_CHANGED}"
-    echo "any_changed=true" >> "$GITHUB_OUTPUT"
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=any_changed::true"
+    else
+      echo "any_changed=true" >> "$GITHUB_OUTPUT"
+    fi
   else
-    echo "any_changed=false" >> "$GITHUB_OUTPUT"
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=any_changed::false"
+    else
+      echo "any_changed=false" >> "$GITHUB_OUTPUT"
+    fi
   fi
 
   OTHER_CHANGED=""
@@ -154,19 +164,38 @@ else
 
   if [[ -n "${OTHER_CHANGED}" && "${OTHER_CHANGED}" != "[]" ]]; then
     echo "::debug::Non Matching changed files: ${OTHER_CHANGED}"
-    echo "only_changed=false" >> "$GITHUB_OUTPUT"
-    echo "other_changed_files=$OTHER_CHANGED" >> "$GITHUB_OUTPUT"
+
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=only_changed::false"
+      echo "::set-output name=other_changed_files::$OTHER_CHANGED"
+    else
+      echo "only_changed=false" >> "$GITHUB_OUTPUT"
+      echo "other_changed_files=$OTHER_CHANGED" >> "$GITHUB_OUTPUT"
+    fi
+
   elif [[ -n "${ALL_CHANGED}" ]]; then
-    echo "only_changed=true" >> "$GITHUB_OUTPUT"
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=only_changed::true"
+    else
+      echo "only_changed=true" >> "$GITHUB_OUTPUT"
+    fi
   fi
 
   ALL_OTHER_MODIFIED=$(get_diff "$INPUT_PREVIOUS_SHA" "$INPUT_CURRENT_SHA" "ACMRD" | awk -v d="|" '{s=(NR==1?s:s d)$0}END{print s}')
 
   if [[ -n "${ALL_MODIFIED}" ]]; then
     echo "::debug::Matching modified files: ${ALL_MODIFIED}"
-    echo "any_modified=true" >> "$GITHUB_OUTPUT"
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=any_modified::true"
+    else
+      echo "any_modified=true" >> "$GITHUB_OUTPUT"
+    fi
   else
-    echo "any_modified=false" >> "$GITHUB_OUTPUT"
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=any_modified::false"
+    else
+      echo "any_modified=false" >> "$GITHUB_OUTPUT"
+    fi
   fi
 
   OTHER_MODIFIED=""
@@ -187,19 +216,37 @@ else
 
   if [[ -n "${OTHER_MODIFIED}" && "$OTHER_MODIFIED" != "[]" ]]; then
     echo "::debug::Non Matching modified files: ${OTHER_MODIFIED}"
-    echo "only_modified=false" >> "$GITHUB_OUTPUT"
-    echo "other_modified_files=$OTHER_MODIFIED" >> "$GITHUB_OUTPUT"
+
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=only_modified::false"
+      echo "::set-output name=other_modified_files::$OTHER_MODIFIED"
+    else
+      echo "only_modified=false" >> "$GITHUB_OUTPUT"
+      echo "other_modified_files=$OTHER_MODIFIED" >> "$GITHUB_OUTPUT"
+    fi
   elif [[ -n "${ALL_MODIFIED}" ]]; then
-    echo "only_modified=true" >> "$GITHUB_OUTPUT"
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=only_modified::true"
+    else
+      echo "only_modified=true" >> "$GITHUB_OUTPUT"
+    fi
   fi
 
   ALL_OTHER_DELETED=$(get_diff "$INPUT_PREVIOUS_SHA" "$INPUT_CURRENT_SHA" D | awk -v d="|" '{s=(NR==1?s:s d)$0}END{print s}')
 
   if [[ -n "${DELETED}" ]]; then
     echo "::debug::Matching deleted files: ${DELETED}"
-    echo "any_deleted=true" >> "$GITHUB_OUTPUT"
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=any_deleted::true"
+    else
+      echo "any_deleted=true" >> "$GITHUB_OUTPUT"
+    fi
   else
-    echo "any_deleted=false" >> "$GITHUB_OUTPUT"
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=any_deleted::false"
+    else
+      echo "any_deleted=false" >> "$GITHUB_OUTPUT"
+    fi
   fi
 
   OTHER_DELETED=""
@@ -220,10 +267,19 @@ else
 
   if [[ -n "${OTHER_DELETED}" && "${OTHER_DELETED}" != "[]" ]]; then
     echo "::debug::Non Matching deleted files: ${OTHER_DELETED}"
-    echo "only_deleted=false" >> "$GITHUB_OUTPUT"
-    echo "other_deleted_files=$OTHER_DELETED" >> "$GITHUB_OUTPUT"
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=only_deleted::false"
+      echo "::set-output name=other_deleted_files::$OTHER_DELETED"
+    else
+      echo "only_deleted=false" >> "$GITHUB_OUTPUT"
+      echo "other_deleted_files=$OTHER_DELETED" >> "$GITHUB_OUTPUT"
+    fi
   elif [[ -n "${DELETED}" ]]; then
-    echo "only_deleted=true" >> "$GITHUB_OUTPUT"
+    if [[ -z "$GITHUB_OUTPUT" ]]; then
+      echo "::set-output name=only_deleted::true"
+    else
+      echo "only_deleted=true" >> "$GITHUB_OUTPUT"
+    fi
   fi
   if [[ "$INPUT_JSON" == "false" ]]; then
     ADDED=$(echo "${ADDED}" | awk '{gsub(/\|/,"\n"); print $0;}' | awk -v d="$INPUT_SEPARATOR" '{s=(NR==1?s:s d)$0}END{print s}')
@@ -267,7 +323,20 @@ if [[ $INPUT_INCLUDE_ALL_OLD_NEW_RENAMED_FILES == "true" ]]; then
   echo "::debug::All old & new renamed files: $ALL_OLD_NEW_RENAMED"
 fi
 
-cat <<EOF >> "$GITHUB_OUTPUT"
+if [[ -z "$GITHUB_OUTPUT" ]]; then
+  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::$RENAMED"
+  echo "::set-output name=type_changed_files::$TYPE_CHANGED"
+  echo "::set-output name=unmerged_files::$UNMERGED"
+  echo "::set-output name=unknown_files::$UNKNOWN"
+  echo "::set-output name=all_changed_and_modified_files::$ALL_CHANGED_AND_MODIFIED"
+  echo "::set-output name=all_changed_files::$ALL_CHANGED"
+  echo "::set-output name=all_modified_files::$ALL_MODIFIED"
+else
+  cat <<EOF >> "$GITHUB_OUTPUT"
 added_files=$ADDED
 copied_files=$COPIED
 deleted_files=$DELETED
@@ -280,8 +349,14 @@ all_changed_and_modified_files=$ALL_CHANGED_AND_MODIFIED
 all_changed_files=$ALL_CHANGED
 all_modified_files=$ALL_MODIFIED
 EOF
+fi
+
 if [[ $INPUT_INCLUDE_ALL_OLD_NEW_RENAMED_FILES == "true" ]]; then
-  echo "all_old_new_renamed_files=$ALL_OLD_NEW_RENAMED" >> "$GITHUB_OUTPUT"
+  if [[ -z "$GITHUB_OUTPUT" ]]; then
+    echo "::set-output name=all_old_new_renamed_files::$ALL_OLD_NEW_RENAMED"
+  else
+    echo "all_old_new_renamed_files=$ALL_OLD_NEW_RENAMED" >> "$GITHUB_OUTPUT"
+  fi
 fi
 
 echo "::endgroup::"
diff --git a/get-sha.sh b/get-sha.sh
deleted file mode 100644
index 8ffdfc11..00000000
--- a/get-sha.sh
+++ /dev/null
@@ -1,24 +0,0 @@
-#!/usr/bin/env bash
-
-set -eu
-
-if [[ -n $INPUT_PATH ]]; then
-  REPO_DIR="$GITHUB_WORKSPACE/$INPUT_PATH"
-
-  echo "Resolving repository path: $REPO_DIR"
-  if [[ ! -d "$REPO_DIR" ]]; then
-    echo "::error::Invalid repository path: $REPO_DIR"
-    exit 1
-  fi
-  cd "$REPO_DIR"
-fi
-
-if [[ -n "$INPUT_UNTIL" ]]; then
-  SHA=$(git log -1 --format="%H" --date=local --until="$INPUT_UNTIL")
-  if [[ -z "$SHA" ]]; then
-    echo "::warning::The SHA for date '$INPUT_UNTIL' couldn't be determined, falling back to the current sha."
-  fi
-  echo "sha=$SHA" >> "$GITHUB_OUTPUT"
-else
-  echo "sha=$INPUT_SHA" >> "$GITHUB_OUTPUT"
-fi