diff --git a/.github/workflows/use-action.yaml b/.github/workflows/use-action.yaml
index b81be84..3a9879d 100644
--- a/.github/workflows/use-action.yaml
+++ b/.github/workflows/use-action.yaml
@@ -15,7 +15,7 @@ jobs:
       - uses: actions/checkout@v2
 
       # Minimal publish
-      - uses: imjasonh/setup-ko@v0.1
+      - uses: imjasonh/setup-ko@main
       - run: ko publish --bare ./
 
       # Install an old release.
diff --git a/action.yml b/action.yml
index 062b495..d05aaa1 100644
--- a/action.yml
+++ b/action.yml
@@ -29,9 +29,14 @@ runs:
         tag="${{ inputs.version }}"
       esac
 
+      os=${{ runner.os }}
+      if [[ $os == "macOS" ]]; then
+        os="Darwin"
+      fi
+
       if [[ ! -z ${tag} ]]; then
-        echo "Installing ko @ ${tag}"
-        curl -fsL https://github.com/google/ko/releases/download/${tag}/ko_${tag:1}_Linux_x86_64.tar.gz | sudo tar xzf - -C /usr/local/bin ko
+        echo "Installing ko @ ${tag} for ${os}"
+        curl -fsL https://github.com/google/ko/releases/download/${tag}/ko_${tag:1}_${os}_x86_64.tar.gz | sudo tar xzf - -C /usr/local/bin ko
       fi
 
       # NB: username doesn't seem to matter.