diff --git a/style/cpp/.clang-tidy b/style/cpp/.clang-tidy
index c566465..42026ac 100644
--- a/style/cpp/.clang-tidy
+++ b/style/cpp/.clang-tidy
@@ -9,6 +9,9 @@
   - { key: readability-function-size.ParameterThreshold,        value: 6 }  # [2]
   - { key: readability-function-cognitive-complexity.Threshold, value: 25 } # [3]
 
+WarningsAsErrors: '*'
+HeaderFileRegex: '(?!^subprojects).*'
+
 # [1] https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#f3-keep-functions-short-and-simple
 # [2] https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#f2-a-function-should-perform-a-single-logical-operation
 # [3] https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#f3-keep-functions-short-and-simple