diff --git a/CHANGELOG.md b/CHANGELOG.md
index 69b89252..f4c7d01e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - `--min-free-space=N` command-line argument to fail if free space is below requred value
 
 ### Changed
+- Fix copy/paste error to allow additional warnings for a platform
 - Properly report compile errors in GitHub Actions (#296)
 - Put build artifacts in a separate directory to reduce clutter.
 - Change 266 files from CRLF to LF.
diff --git a/SampleProjects/TestSomething/.arduino-ci.yml b/SampleProjects/TestSomething/.arduino-ci.yml
index f9890177..109fa0f3 100644
--- a/SampleProjects/TestSomething/.arduino-ci.yml
+++ b/SampleProjects/TestSomething/.arduino-ci.yml
@@ -1,3 +1,18 @@
+platforms:
+  uno:
+    board: arduino:avr:uno
+    package: arduino:avr
+    gcc:
+      features:
+      defines:
+        - __AVR__
+        - __AVR_ATmega328P__
+        - ARDUINO_ARCH_AVR
+        - ARDUINO_AVR_UNO
+      warnings:
+        - no-unknown-attributes
+      flags:
+
 unittest:
   platforms:
     - uno
diff --git a/lib/arduino_ci/cpp_library.rb b/lib/arduino_ci/cpp_library.rb
index cedd3ba2..2af31c55 100644
--- a/lib/arduino_ci/cpp_library.rb
+++ b/lib/arduino_ci/cpp_library.rb
@@ -443,7 +443,7 @@ def feature_args(ci_gcc_config)
     def warning_args(ci_gcc_config)
       return [] if ci_gcc_config[:warnings].nil?
 
-      ci_gcc_config[:features].map { |w| "-W#{w}" }
+      ci_gcc_config[:warnings].map { |w| "-W#{w}" }
     end
 
     # GCC command line arguments for defines (e.g. -Dhave_something)