diff --git a/.github/actionlint.yaml b/.github/actionlint.yaml
new file mode 100644
index 000000000..8a9a13016
--- /dev/null
+++ b/.github/actionlint.yaml
@@ -0,0 +1,2 @@
+# actionlint configuration
+# https://github.com/rhysd/actionlint/blob/main/docs/config.md
diff --git a/.github/settings.yml b/.github/settings.yml
index e78499030..d5c2434e1 100644
--- a/.github/settings.yml
+++ b/.github/settings.yml
@@ -1,4 +1,3 @@
----
 branches:
   - name: main
     protection:
diff --git a/.github/stale.yml b/.github/stale.yml
index d9fa51d57..e7da8955d 100644
--- a/.github/stale.yml
+++ b/.github/stale.yml
@@ -68,10 +68,7 @@ pull:
   daysUntilClose: 14
   daysUntilStale: 60
   markComment: >
-    Hello 👋 Looks like there was no activity on this amazing PR for the last 60 days.
-    **Do you mind updating us on the status?** Is there anything we can help with? If you plan to still work on it, just comment on this PR or push a commit. Thanks! 🤗
-    
-    If there will be no activity in the next 2 weeks, this issue will be closed (we can always reopen a PR if you get back to this!).
+    Hello 👋 Looks like there was no activity on this amazing PR for the last 60 days. **Do you mind updating us on the status?** Is there anything we can help with? If you plan to still work on it, just comment on this PR or push a commit. Thanks! 🤗 #magic___^_^___line If there will be no activity in the next 2 weeks, this issue will be closed (we can always reopen a PR if you get back to this!).
   # unmarkComment: No need for unmark comment.
   closeComment: >
     Closing for now as promised, let us know if you need this to be reopened! 🤗
@@ -79,10 +76,7 @@ issues:
   daysUntilClose: 90
   daysUntilStale: 180
   markComment: >
-    Hello 👋 Looks like there was no activity on this issue for the last 3 months.
-    **Do you mind updating us on the status?** Is this still reproducible or needed? If yes, just comment on this PR or push a commit. Thanks! 🤗
-    
-    If there will be no activity in the next 4 weeks, this issue will be closed (we can always reopen an issue if we need!).
+    Hello 👋 Looks like there was no activity on this issue for the last 3 months. **Do you mind updating us on the status?** Is this still reproducible or needed? If yes, just comment on this PR or push a commit. Thanks! 🤗 #magic___^_^___line If there will be no activity in the next 4 weeks, this issue will be closed (we can always reopen an issue if we need!).
   # unmarkComment: No need for unmark comment.
   closeComment: >
     Closing for now as promised, let us know if you need this to be reopened! 🤗
diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index 8ade528ba..7963db46c 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -13,10 +13,10 @@ name: "CodeQL"
 
 on:
   push:
-    branches: [ main ]
+    branches: [main]
   pull_request:
     # The branches below must be a subset of the branches above
-    branches: [ main ]
+    branches: [main]
   schedule:
     - cron: '31 21 * * 6'
 
@@ -40,39 +40,39 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        language: [ 'go' ]
+        language: ['go']
         # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python', 'ruby' ]
         # Learn more about CodeQL language support at https://git.io/codeql-language-support
 
     steps:
-    - name: Checkout repository
-      uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+      - name: Checkout repository
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
-    # Initializes the CodeQL tools for scanning.
-    - name: Initialize CodeQL
-      uses: github/codeql-action/init@3599b3baa15b485a2e49ef411a7a4bb2452e7f93 # v3.29.5
-      with:
-        languages: ${{ matrix.language }}
-        # If you wish to specify custom queries, you can do so here or in a config file.
-        # By default, queries listed here will override any specified in a config file.
-        # Prefix the list here with "+" to use these queries and those in the config file.
-        # queries: ./path/to/local/query, your-org/your-repo/queries@main
+      # Initializes the CodeQL tools for scanning.
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@3599b3baa15b485a2e49ef411a7a4bb2452e7f93 # v3.29.5
+        with:
+          languages: ${{ matrix.language }}
+          # If you wish to specify custom queries, you can do so here or in a config file.
+          # By default, queries listed here will override any specified in a config file.
+          # Prefix the list here with "+" to use these queries and those in the config file.
+          # queries: ./path/to/local/query, your-org/your-repo/queries@main
 
-    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
-    # If this step fails, then you should remove it and run the build manually (see below)
-    - name: Autobuild
-      uses: github/codeql-action/autobuild@3599b3baa15b485a2e49ef411a7a4bb2452e7f93 # v3.29.5
+      # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
+      # If this step fails, then you should remove it and run the build manually (see below)
+      - name: Autobuild
+        uses: github/codeql-action/autobuild@3599b3baa15b485a2e49ef411a7a4bb2452e7f93 # v3.29.5
 
-    # ℹ️ Command-line programs to run using the OS shell.
-    # 📚 https://git.io/JvXDl
+      # ℹ️ Command-line programs to run using the OS shell.
+      # 📚 https://git.io/JvXDl
 
-    # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
-    #    and modify them (or add more) to build your code if your project
-    #    uses a compiled language
+      # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
+      #    and modify them (or add more) to build your code if your project
+      #    uses a compiled language
 
-    #- run: |
-    #   make bootstrap
-    #   make release
+      #- run: |
+      #   make bootstrap
+      #   make release
 
-    - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@3599b3baa15b485a2e49ef411a7a4bb2452e7f93 # v3.29.5
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@3599b3baa15b485a2e49ef411a7a4bb2452e7f93 # v3.29.5
diff --git a/.github/workflows/container_description.yml b/.github/workflows/container_description.yml
index c7c7ac776..74f72d245 100644
--- a/.github/workflows/container_description.yml
+++ b/.github/workflows/container_description.yml
@@ -1,4 +1,3 @@
----
 name: Push README to Docker Hub
 on:
   push:
@@ -6,7 +5,7 @@ on:
       - "README.md"
       - "README-containers.md"
       - ".github/workflows/container_description.yml"
-    branches: [ main, master ]
+    branches: [main, master]
 
 permissions:
   contents: read
@@ -22,7 +21,7 @@ jobs:
         with:
           persist-credentials: false
       - name: Set docker hub repo name
-        run: echo "DOCKER_REPO_NAME=$(make docker-repo-name)" >> $GITHUB_ENV
+        run: echo "DOCKER_REPO_NAME=$(make docker-repo-name)" >> "$GITHUB_ENV"
       - name: Push README to Dockerhub
         uses: christian-korneck/update-container-description-action@d36005551adeaba9698d8d67a296bd16fa91f8e8 # v1
         env:
@@ -46,9 +45,9 @@ jobs:
         with:
           persist-credentials: false
       - name: Set quay.io org name
-        run: echo "DOCKER_REPO=$(echo quay.io/${GITHUB_REPOSITORY_OWNER} | tr -d '-')" >> $GITHUB_ENV
+        run: echo "DOCKER_REPO=$(echo "quay.io/${GITHUB_REPOSITORY_OWNER}" | tr -d '-')" >> "$GITHUB_ENV"
       - name: Set quay.io repo name
-        run: echo "DOCKER_REPO_NAME=$(make docker-repo-name)" >> $GITHUB_ENV
+        run: echo "DOCKER_REPO_NAME=$(make docker-repo-name)" >> "$GITHUB_ENV"
       - name: Push README to quay.io
         uses: christian-korneck/update-container-description-action@d36005551adeaba9698d8d67a296bd16fa91f8e8 # v1
         env:
diff --git a/.github/workflows/golangci-lint.yml b/.github/workflows/golangci-lint.yml
index cde2b76f2..e3b828b02 100644
--- a/.github/workflows/golangci-lint.yml
+++ b/.github/workflows/golangci-lint.yml
@@ -1,4 +1,3 @@
----
 # This action is synced from https://github.com/prometheus/prometheus
 name: golangci-lint
 on:
@@ -12,14 +11,14 @@ on:
       - ".golangci.yml"
   pull_request:
 
-permissions:  # added using https://github.com/step-security/secure-repo
+permissions: # added using https://github.com/step-security/secure-repo
   contents: read
 
 jobs:
   golangci:
     permissions:
-      contents: read  # for actions/checkout to fetch code
-      pull-requests: read  # for golangci/golangci-lint-action to fetch pull requests
+      contents: read # for actions/checkout to fetch code
+      pull-requests: read # for golangci/golangci-lint-action to fetch pull requests
     name: lint
     runs-on: ubuntu-latest
     steps:
diff --git a/.github/workflows/scorecard.yml b/.github/workflows/scorecard.yml
index a2dc3d2fb..241f7e44b 100644
--- a/.github/workflows/scorecard.yml
+++ b/.github/workflows/scorecard.yml
@@ -9,7 +9,7 @@ on:
   schedule:
     - cron: '22 1 * * 0'
   push:
-    branches: [ "main" ]
+    branches: ["main"]
 
 # Declare default permissions as read only.
 permissions: read-all
diff --git a/.github/workflows/update-go-versions.yml b/.github/workflows/update-go-versions.yml
index 3e2a05139..4685af2c2 100644
--- a/.github/workflows/update-go-versions.yml
+++ b/.github/workflows/update-go-versions.yml
@@ -1,4 +1,3 @@
----
 name: Generate Metric files for new Go version
 
 on:
diff --git a/.github/workflows/go.yml b/.github/workflows/validate.yml
similarity index 66%
rename from .github/workflows/go.yml
rename to .github/workflows/validate.yml
index 1bf5121ce..c6f0493e1 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/validate.yml
@@ -1,68 +1,89 @@
----
-name: Go
-on:
-  pull_request:
-  push:
-    branches:
-      - main
-      - "release-*"
-
-# Modified to avoid canceling all matrix jobs when one fails
-# Each job type will have its own concurrency group
-concurrency:
-  group: ${{ github.workflow }}-${{ github.job }}-${{ (github.event.pull_request && github.event.pull_request.number) || github.ref || github.run_id }}
-  cancel-in-progress: true
-
-# Minimal permissions to be inherited by any job that don't declare it's own permissions
-permissions:
-  contents: read
-
-jobs:
-  supportedVersions:
-    name: Fetch supported Go versions
-    runs-on: ubuntu-latest
-    outputs:
-        supported_versions: ${{ steps.matrix.outputs.supported_versions }}
-    steps:
-      - name: Checkout code
+name: Validate
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+      - "release-*"
+
+# Modified to avoid canceling all matrix jobs when one fails
+# Each job type will have its own concurrency group
+concurrency:
+  group: ${{ github.workflow }}-${{ github.job }}-${{ (github.event.pull_request && github.event.pull_request.number) || github.ref || github.run_id }}
+  cancel-in-progress: true
+
+# Minimal permissions to be inherited by any job that don't declare it's own permissions
+permissions:
+  contents: read
+
+jobs:
+  supported_versions:
+    name: Fetch supported Go versions
+    runs-on: ubuntu-latest
+    outputs:
+      supported_versions: ${{ steps.matrix.outputs.supported_versions }}
+    steps:
+      - name: Checkout code
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-      - name: Read supported_go_versions.txt
-        id: matrix
-        run: |
-            versions=$(cat supported_go_versions.txt)
-            matrix="[$(echo "$versions" | sed 's/\(.*\)/"\1"/' | paste -s -d,)]"
-            echo "supported_versions=$matrix" >> $GITHUB_OUTPUT
-
-  test:
-    name: Tests (${{ matrix.go_version }})
-    runs-on: ubuntu-latest
-    needs: supportedVersions
-    # Set fail-fast to false to ensure all Go versions are tested regardless of failures
-    strategy:
-      fail-fast: false
-      matrix:
-        go_version: ${{ fromJSON(needs.supportedVersions.outputs.supported_versions) }}
-    # Define concurrency at the job level for matrix jobs
-    concurrency:
-      group: ${{ github.workflow }}-test-${{ matrix.go_version }}-${{ (github.event.pull_request && github.event.pull_request.number) || github.ref || github.run_id }}
-      cancel-in-progress: true
-
-    steps:
-      - name: Checkout code
+      - name: Read supported_go_versions.txt
+        id: matrix
+        run: |
+          versions="$(cat supported_go_versions.txt)"
+          matrix="[$(echo "$versions" | sed 's/\(.*\)/"\1"/' | paste -s -d,)]"
+          echo "supported_versions=$matrix" >> "$GITHUB_OUTPUT"
+
+  test:
+    name: Tests (${{ matrix.go_version }})
+    runs-on: ubuntu-latest
+    needs: supported_versions
+    # Set fail-fast to false to ensure all Go versions are tested regardless of failures
+    strategy:
+      fail-fast: false
+      matrix:
+        go_version: ${{ fromJSON(needs.supported_versions.outputs.supported_versions) }}
+    # Define concurrency at the job level for matrix jobs
+    concurrency:
+      group: ${{ github.workflow }}-test-${{ matrix.go_version }}-${{ (github.event.pull_request && github.event.pull_request.number) || github.ref || github.run_id }}
+      cancel-in-progress: true
+
+    steps:
+      - name: Checkout code
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-
-      - name: Set up Go ${{ matrix.go_version }}
-        uses: actions/setup-go@v6.0.0
-        with:
-          go-version: ${{ matrix.go_version }}
-          check-latest: true
-          cache-dependency-path: go.sum
-
-      - name: Run tests and check license
-        run: make check_license test
-        env:
-          CI: true
-
-      - name: Run style and unused
-        if: ${{ matrix.go_version == '1.22' }}
-        run: make style unused
+
+      - name: Check for CRLF line endings
+        run: make check-crlf
+
+      - name: Set up Go ${{ matrix.go_version }}
+        uses: actions/setup-go@v6.0.0
+        with:
+          go-version: ${{ matrix.go_version }}
+          check-latest: true
+          cache-dependency-path: go.sum
+
+      - name: Run tests and check license
+        run: make check_license test
+        env:
+          CI: true
+
+      - name: Run style and unused
+        if: ${{ matrix.go_version == '1.22' }}
+        run: make style unused
+
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+
+      - name: Set up Go
+        uses: actions/setup-go@v6.0.0
+        with:
+          go-version: stable
+          check-latest: true
+
+      - name: Lint YAML files
+        run: make lint-yaml
+
+      - name: Lint GitHub Actions workflows
+        run: make lint-actions
diff --git a/.yamlfmt b/.yamlfmt
new file mode 100644
index 000000000..65f1cfcdb
--- /dev/null
+++ b/.yamlfmt
@@ -0,0 +1,17 @@
+# yamlfmt configuration
+# https://github.com/google/yamlfmt
+
+doublestar: true
+
+exclude:
+  - "**/testdata/**"
+  - "**/*testdata*/**"
+
+gitignore_excludes: true
+
+formatter:
+  type: basic
+  indent: 2
+  include_document_start: false
+  retain_line_breaks: true
+  max_line_length: 0
diff --git a/Makefile b/Makefile
index 2a5817c02..6e5f0c7da 100644
--- a/Makefile
+++ b/Makefile
@@ -65,3 +65,47 @@ test-exp:
 .PHONY: test-exp-short
 test-exp-short:
 	cd exp && $(GOTEST) -short $(GOOPTS) $(pkgs)
+
+YAMLFMT := $(FIRST_GOPATH)/bin/yamlfmt
+ACTIONLINT := $(FIRST_GOPATH)/bin/actionlint
+
+$(YAMLFMT):
+	go install github.com/google/yamlfmt/cmd/yamlfmt@latest
+
+$(ACTIONLINT):
+	go install github.com/rhysd/actionlint/cmd/actionlint@latest
+
+.PHONY: format-yaml
+format-yaml: $(YAMLFMT)
+	@echo ">> formatting YAML files"
+	$(YAMLFMT) -dstar '**/*.yml' '**/*.yaml'
+
+.PHONY: lint-yaml
+lint-yaml: $(YAMLFMT)
+	@echo ">> linting YAML files"
+	$(YAMLFMT) -lint -dstar '**/*.yml' '**/*.yaml'
+
+.PHONY: lint-actions
+lint-actions: $(ACTIONLINT)
+	@echo ">> linting GitHub Actions workflows"
+	$(ACTIONLINT)
+
+.PHONY: check-crlf
+check-crlf:
+	@echo ">> checking for CRLF line endings"
+	@files=$$(find . -type f -not -path "*/\.*" -not -path "*/vendor/*" -exec file {} \; | grep CRLF | cut -d: -f1); \
+	if [ -n "$$files" ]; then \
+		echo "Files with CRLF line endings found:"; \
+		echo "$$files"; \
+		echo "Run 'make fix-crlf' to fix them"; \
+		exit 1; \
+	fi
+
+.PHONY: fix-crlf
+fix-crlf:
+	@echo ">> fixing CRLF line endings"
+	@files=$$(find . -type f -not -path "*/\.*" -not -path "*/vendor/*" -exec file {} \; | grep CRLF | cut -d: -f1); \
+	for file in $$files; do \
+		tr -d '\r' < "$$file" > "$$file.tmp" && mv "$$file.tmp" "$$file"; \
+	done
+	@echo ">> CRLF line endings fixed"
diff --git a/api/prometheus/v1/api_bench_test.go b/api/prometheus/v1/api_bench_test.go
index f1f8000ef..97f502e56 100644
--- a/api/prometheus/v1/api_bench_test.go
+++ b/api/prometheus/v1/api_bench_test.go
@@ -100,7 +100,7 @@ func generateData(timeseries, datapoints int) (floatMatrix, histogramMatrix mode
 		floatMatrix = append(floatMatrix, fss)
 		histogramMatrix = append(histogramMatrix, hss)
 	}
-	return
+	return floatMatrix, histogramMatrix
 }
 
 func BenchmarkSamplesJsonSerialization(b *testing.B) {
diff --git a/exp/api/remote/genproto/buf.gen.yaml b/exp/api/remote/genproto/buf.gen.yaml
index 63e34a0d7..64369538a 100644
--- a/exp/api/remote/genproto/buf.gen.yaml
+++ b/exp/api/remote/genproto/buf.gen.yaml
@@ -2,20 +2,20 @@
 version: v2
 
 plugins:
-- remote: buf.build/protocolbuffers/go:v1.31.0
-  out: .
-  opt:
-  - Mio/prometheus/write/v2/types.proto=./v2
+  - remote: buf.build/protocolbuffers/go:v1.31.0
+    out: .
+    opt:
+      - Mio/prometheus/write/v2/types.proto=./v2
 
-# vtproto for efficiency utilities like pooling etc.
-# https://buf.build/community/planetscale-vtprotobuf?version=v0.6.0
-- remote: buf.build/community/planetscale-vtprotobuf:v0.6.0
-  out: .
-  opt:
-  - Mio/prometheus/write/v2/types.proto=./v2
-  - features=marshal+unmarshal+size
+  # vtproto for efficiency utilities like pooling etc.
+  # https://buf.build/community/planetscale-vtprotobuf?version=v0.6.0
+  - remote: buf.build/community/planetscale-vtprotobuf:v0.6.0
+    out: .
+    opt:
+      - Mio/prometheus/write/v2/types.proto=./v2
+      - features=marshal+unmarshal+size
 
 inputs:
-- module: buf.build/prometheus/prometheus:5b212ab78fb7460e831cf7ff2d83e385
-  types:
-  - "io.prometheus.write.v2.Request"
+  - module: buf.build/prometheus/prometheus:5b212ab78fb7460e831cf7ff2d83e385
+    types:
+      - "io.prometheus.write.v2.Request"
diff --git a/internal/github.com/golang/gddo/httputil/header/header.go b/internal/github.com/golang/gddo/httputil/header/header.go
index 8547c8dfd..820bf436a 100644
--- a/internal/github.com/golang/gddo/httputil/header/header.go
+++ b/internal/github.com/golang/gddo/httputil/header/header.go
@@ -90,7 +90,7 @@ loop:
 			s = skipSpace(s[1:])
 		}
 	}
-	return
+	return specs
 }
 
 func skipSpace(s string) (rest string) {
diff --git a/prometheus/example_clustermanager_test.go b/prometheus/example_clustermanager_test.go
index 92b61ca85..efe06f758 100644
--- a/prometheus/example_clustermanager_test.go
+++ b/prometheus/example_clustermanager_test.go
@@ -53,7 +53,7 @@ func (c *ClusterManager) ReallyExpensiveAssessmentOfTheSystemState() (
 		"foo.example.org": 6.023e23,
 		"bar.example.org": 3.14,
 	}
-	return
+	return oomCountByHost, ramUsageByHost
 }
 
 // ClusterManagerCollector implements the Collector interface.
diff --git a/prometheus/graphite/bridge_test.go b/prometheus/graphite/bridge_test.go
index 8c596d5ac..10a674a2c 100644
--- a/prometheus/graphite/bridge_test.go
+++ b/prometheus/graphite/bridge_test.go
@@ -342,7 +342,7 @@ func stringToLines(s string) (lines []string, err error) {
 		lines = append(lines, scanner.Text())
 	}
 	err = scanner.Err()
-	return
+	return lines, err
 }
 
 func TestPush(t *testing.T) {
diff --git a/prometheus/promhttp/instrument_server.go b/prometheus/promhttp/instrument_server.go
index 9332b0249..66878b80a 100644
--- a/prometheus/promhttp/instrument_server.go
+++ b/prometheus/promhttp/instrument_server.go
@@ -366,7 +366,7 @@ func checkLabels(c prometheus.Collector) (code, method bool) {
 			panic("metric partitioned with non-supported labels")
 		}
 	}
-	return
+	return code, method
 }
 
 func isLabelCurried(c prometheus.Collector, label string) bool {
diff --git a/prometheus/promhttp/instrument_server_test.go b/prometheus/promhttp/instrument_server_test.go
index 45640e605..e769cb9ba 100644
--- a/prometheus/promhttp/instrument_server_test.go
+++ b/prometheus/promhttp/instrument_server_test.go
@@ -324,7 +324,7 @@ func TestLabels(t *testing.T) {
 				panic("metric partitioned with non-supported labels for this test")
 			}
 		}
-		return
+		return gotCode, gotMethod
 	}
 	equalLabels := func(gotLabels, wantLabels prometheus.Labels) bool {
 		if len(gotLabels) != len(wantLabels) {
diff --git a/prometheus/summary_test.go b/prometheus/summary_test.go
index 440237206..2067449b4 100644
--- a/prometheus/summary_test.go
+++ b/prometheus/summary_test.go
@@ -422,7 +422,7 @@ func getBounds(vars []float64, q, ε float64) (minBound, maxBound float64) {
 	if upper < len(vars) {
 		maxBound = vars[upper-1]
 	}
-	return
+	return minBound, maxBound
 }
 
 func TestSummaryVecCreatedTimestampWithDeletes(t *testing.T) {
diff --git a/tutorials/whatsup/internal/acceptance_test.go b/tutorials/whatsup/internal/acceptance_test.go
index 38533c495..57848a9b9 100644
--- a/tutorials/whatsup/internal/acceptance_test.go
+++ b/tutorials/whatsup/internal/acceptance_test.go
@@ -78,5 +78,4 @@ func TestAcceptance(t *testing.T) {
 	if gotErr {
 		fmt.Println("Got this response from ", fmt.Sprintf("http://localhost:%v", WhatsupPort), ":", metrics)
 	}
-
 }
diff --git a/tutorials/whatsup/main.go b/tutorials/whatsup/main.go
index 5943eefb0..15ebd4e72 100644
--- a/tutorials/whatsup/main.go
+++ b/tutorials/whatsup/main.go
@@ -73,7 +73,7 @@ func runMain(opts internal.Config) (err error) {
 	m := http.NewServeMux()
 	// Create HTTP handler for Prometheus metrics.
 	// TODO
-	//m.Handle("/metrics", ...
+	// m.Handle("/metrics", ...
 
 	promClient, err := api.NewClient(api.Config{
 		Client:  &http.Client{Transport: instrumentRoundTripper(nil, "prometheus", http.DefaultTransport)},