diff --git a/CMakeLists.txt b/CMakeLists.txt
index b03b70b..354084f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -327,16 +327,11 @@ endif()
 include(CTest)
 include(Catch)
 if(BUILD_TESTING)
-    if(APPLE)
-        # On macOS, only build tests for debug builds
-        if(CMAKE_BUILD_TYPE STREQUAL "Debug")
-            add_subdirectory(test/cpp)
-        endif()
-    elseif(CMAKE_CROSSCOMPILING)
+    if(CMAKE_CROSSCOMPILING)
         # Skip running tests when cross-compiling
         message(STATUS "Skipping tests during cross-compilation")
     else()
-        # On other platforms (Linux), build tests for all configurations
+        # Build tests for all platforms and configurations
         add_subdirectory(test/cpp)
     endif()
 endif()
diff --git a/src/caching_file_provider.cpp b/src/caching_file_provider.cpp
index 79f9cea..950ed0c 100644
--- a/src/caching_file_provider.cpp
+++ b/src/caching_file_provider.cpp
@@ -111,16 +111,18 @@ std::string CachingFileProvider::ReadFile(const std::string& path) {
             evictLRU(content_size);
         }
 
-        // Add to cache
+        // Add to cache only if not already inserted by a concurrent thread
         CacheEntry entry;
         entry.content = content;
         entry.expires_at = std::chrono::steady_clock::now() + _config.ttl;
         entry.last_access = std::chrono::steady_clock::now();
         entry.size_bytes = content_size;
 
-        _cache[path] = std::move(entry);
-        _stats.current_entries.fetch_add(1);
-        _stats.current_size_bytes.fetch_add(content_size);
+        auto [it, inserted] = _cache.emplace(path, std::move(entry));
+        if (inserted) {
+            _stats.current_entries.fetch_add(1);
+            _stats.current_size_bytes.fetch_add(content_size);
+        }
     }
 
     return content;
diff --git a/test/integration/pyproject.toml b/test/integration/pyproject.toml
index fcc40fd..3a1e618 100644
--- a/test/integration/pyproject.toml
+++ b/test/integration/pyproject.toml
@@ -1,3 +1,10 @@
+[build-system]
+requires = ["setuptools>=61.0"]
+build-backend = "setuptools.build_meta"
+
+[tool.setuptools]
+packages = []
+
 [project]
 name = "flapi-integration-tests"
 version = "0.1.0"
@@ -20,9 +27,6 @@ dependencies = [
     "psutil>=5.9.0",
 ]
 
-[tool.setuptools]
-packages = []
-
 [tool.pytest.ini_options]
 addopts = "-v"
 testpaths = ["."]