diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8f73dd8f..783d05d4 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
+- Put build artifacts in a separate directory to reduce clutter.
 - Change 266 files from CRLF to LF.
 - Update .gitattributes so we have consistent line endings
 - Run tests on push as well as on a pull request so developers can see impact
diff --git a/lib/arduino_ci/cpp_library.rb b/lib/arduino_ci/cpp_library.rb
index 4ad7307f..cedd3ba2 100644
--- a/lib/arduino_ci/cpp_library.rb
+++ b/lib/arduino_ci/cpp_library.rb
@@ -491,7 +491,10 @@ def test_args(aux_libraries, ci_gcc_config)
     # @return [Pathname] path to the compiled test executable
     def build_for_test_with_configuration(test_file, aux_libraries, gcc_binary, ci_gcc_config)
       base = test_file.basename
-      executable = Pathname.new("unittest_#{base}.bin").expand_path
+      # hide build artifacts
+      build_dir = '.arduino_ci'
+      Dir.mkdir build_dir unless File.exist?(build_dir)
+      executable = Pathname.new("#{build_dir}/unittest_#{base}.bin").expand_path
       File.delete(executable) if File.exist?(executable)
       arg_sets = []
       arg_sets << ["-std=c++0x", "-o", executable.to_s, "-DARDUINO=100"]