diff --git a/.github/workflows/restrict-main.yml b/.github/workflows/restrict-main.yml
new file mode 100644
index 0000000..d4316bd
--- /dev/null
+++ b/.github/workflows/restrict-main.yml
@@ -0,0 +1,17 @@
+name: Restrict main merges
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  check-branch:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Ensure PR comes from develop
+        run: |
+          if [ "${{ github.head_ref }}" != "develop" ]; then
+            echo "Only develop can be merged into main."
+            exit 1
+          fi
diff --git a/Sources/ForeFlightKML/Styles/IconStyle.swift b/Sources/ForeFlightKML/Styles/IconStyle.swift
index 720821a..dc80caf 100644
--- a/Sources/ForeFlightKML/Styles/IconStyle.swift
+++ b/Sources/ForeFlightKML/Styles/IconStyle.swift
@@ -130,7 +130,7 @@ public enum CustomIconType: Codable {
         "target": .target,
         "square": .square,
         "placemark_square": .placemarksquare,
-        "placemark_circle": .placemarkcircle,
+        "placemark_circle": .placemarkcircle
     ]
 
     public func encode(to encoder: any Encoder) throws {
diff --git a/Sources/ForeFlightKML/Utils/Protocols.swift b/Sources/ForeFlightKML/Utils/Protocols.swift
index 8783e78..379ca57 100644
--- a/Sources/ForeFlightKML/Utils/Protocols.swift
+++ b/Sources/ForeFlightKML/Utils/Protocols.swift
@@ -60,7 +60,3 @@ public extension KMLSubStyle {
 protocol Building {
     func build(as format: OutputFormat) throws -> BuildResult
 }
-
-protocol Building {
-    func build(as format: OutputFormat) throws -> BuildResult
-}