diff --git a/action.yml b/action.yml
index 4def6f9..0ae0f69 100644
--- a/action.yml
+++ b/action.yml
@@ -9,25 +9,29 @@ inputs:
     description: "Args to pass to scalafmt"
     default: "--list"
     required: false
-  version:
-    description: "Version of scalafmt"
-    default: "3.7.15"
-    required: false
 
 runs:
   using: "composite"
   steps:
+  - shell: bash
+    id: extract-scalafmt-version
+    run: |
+      version=$(perl -ne 'next unless /^\s*version\s*=\s*(\d+\.\d+\.\d+)/; print "$1"; last' .scalafmt.conf)
+      if [ -z "$version" ]; then
+        echo "Failed to extract scalafmt version from .scalafmt.conf"
+        exit 1
+      fi
+      echo "scalafmt_version=$version" >> "$GITHUB_ENV"
   - shell: bash
     run: |
       "$action_path/set-path.sh"
     env:
-      scalafmt_version: ${{ inputs.version }}
       action_path: ${{ github.action_path }}
   - uses: actions/cache/restore@v4
     id: cache
     with:
       path: ${{ env.SCALAFMT_PATH }}
-      key: scalafmt-${{ inputs.version }}
+      key: scalafmt-${{ env.scalafmt_version }}
   - shell: bash
     id: retrieve-scalafmt
     if: ${{ !steps.cache.outputs.cache-hit }}
@@ -45,4 +49,4 @@ runs:
     uses: actions/cache/save@v4
     with:
       path: ${{ env.SCALAFMT_PATH }}
-      key: scalafmt-${{ inputs.version }}
+      key: scalafmt-${{ env.scalafmt_version }}
diff --git a/run-scalafmt.sh b/run-scalafmt.sh
index 6f538b1..7979602 100755
--- a/run-scalafmt.sh
+++ b/run-scalafmt.sh
@@ -3,13 +3,6 @@ output=$(mktemp)
 warnings=$(mktemp)
 errors=$(mktemp)
 
-enforce_scala_format_version() {
-  if [ -e .scalafmt.conf ]; then
-    perl -pi -e 'next unless s/^\s*(version)=.*/$1=$ENV{scalafmt_version}/' .scalafmt.conf
-  fi
-}
-
-enforce_scala_format_version
 scalafmt --non-interactive $args > "$output" 2> "$warnings"
 result=$?
 cat "$output"