diff --git a/.github/workflows/build-debug.yml b/.github/workflows/build-debug.yml
index 0dc6785..809943b 100644
--- a/.github/workflows/build-debug.yml
+++ b/.github/workflows/build-debug.yml
@@ -19,13 +19,6 @@ jobs:
       NUGET_XMLDOC_MODE: skip
     steps:
       - uses: actions/checkout@v2
-      - uses: actions/setup-dotnet@v1
-        with:
-          dotnet-version: 3.1.x
-      - uses: actions/setup-dotnet@v1
-        with:
-          dotnet-version: 5.0.x
-
       # build CommandTools first (using dotnet run command in ZLogger.csproj)
       - run: dotnet build -c Debug src/Ulid
       - run: dotnet build -c Debug src/Ulid.Cli
diff --git a/.github/workflows/build-release.yml b/.github/workflows/build-release.yml
index 096f3f4..9a413fa 100644
--- a/.github/workflows/build-release.yml
+++ b/.github/workflows/build-release.yml
@@ -15,8 +15,6 @@ env:
   GIT_TAG: ${{ github.event.inputs.tag }}
   DRY_RUN: ${{ github.event.inputs.dry_run }}
   DRY_RUN_BRANCH_PREFIX: "test_release"
-  DOTNET_SDK_VERISON_3: 3.1.x
-  DOTNET_SDK_VERISON_5: 5.0.x
 
 jobs:
   update-packagejson:
@@ -85,12 +83,6 @@ jobs:
       - uses: actions/checkout@v2
         with:
           ref: ${{ needs.update-packagejson.outputs.sha }}
-      - uses: actions/setup-dotnet@v1
-        with:
-          dotnet-version: "${{ env.DOTNET_SDK_VERSION_3 }}"
-      - uses: actions/setup-dotnet@v1
-        with:
-          dotnet-version: "${{ env.DOTNET_SDK_VERSION_5 }}"
       # build CommandTools first (using dotnet run command in ZLogger.csproj)
       - run: dotnet build -c Release src/Ulid -p:Version=${{ env.GIT_TAG }}
       - run: dotnet build -c Release src/Ulid.Cli -p:Version=${{ env.GIT_TAG }}
@@ -165,10 +157,6 @@ jobs:
       DOTNET_SKIP_FIRST_TIME_EXPERIENCE: 1
       NUGET_XMLDOC_MODE: skip
     steps:
-      # setup dotnet for nuget push
-      - uses: actions/setup-dotnet@v1
-        with:
-          dotnet-version: "${{ env.DOTNET_SDK_VERSION_3 }}"
       # Create Releases
       - uses: actions/create-release@v1
         id: create_release