diff --git a/generator/CMakeLists.txt b/generator/CMakeLists.txt
index 7ceae6c..9102176 100644
--- a/generator/CMakeLists.txt
+++ b/generator/CMakeLists.txt
@@ -72,4 +72,13 @@ add_reflection_generator_invocation(
 include(TestTarget)
 include(ShellCompletion)
 include(Doxygen)
+
+# add paths for include dirs of c++utilities and RapidJSON to config header so test cases can use it
+set(META_CUSTOM_CONFIG "#define CPP_UTILITIES_INCLUDE_DIRS \"${CPP_UTILITIES_INCLUDE_DIRS}\"\n")
+if(RapidJSON_FOUND)
+    string(APPEND META_CUSTOM_CONFIG "#define RAPIDJSON_INCLUDE_DIRS \"${RAPIDJSON_INCLUDE_DIRS}\"\n")
+endif()
+
+# make config header
 include(ConfigHeader)
+
diff --git a/generator/tests/jsongenerator.cpp b/generator/tests/jsongenerator.cpp
index b1d0150..3129564 100644
--- a/generator/tests/jsongenerator.cpp
+++ b/generator/tests/jsongenerator.cpp
@@ -65,7 +65,7 @@ void JsonGeneratorTests::testGeneratorItself()
 {
     const string inputFilePath(testFilePath("some_structs.h"));
     const vector<const char *> inputFiles{ inputFilePath.data() };
-    const vector<const char *> clangOptions{};
+    const vector<string> clangOptions{"-I" CPP_UTILITIES_INCLUDE_DIRS, "-I" RAPIDJSON_INCLUDE_DIRS};
 
     stringstream buffer;
     JsonSerializationCodeGenerator::Options jsonOptions;
@@ -88,7 +88,7 @@ void JsonGeneratorTests::testCLI()
     string stdout, stderr;
 
     const string inputFilePath(testFilePath("some_structs.h"));
-    const char *const args1[] = { PROJECT_NAME, "-i", inputFilePath.data(), "--json-classes", "TestNamespace2::ThirdPartyStruct", nullptr };
+    const char *const args1[] = { PROJECT_NAME, "-i", inputFilePath.data(), "--json-classes", "TestNamespace2::ThirdPartyStruct", "--clang-opt", "-I" CPP_UTILITIES_INCLUDE_DIRS, "-I" RAPIDJSON_INCLUDE_DIRS, nullptr };
     TESTUTILS_ASSERT_EXEC(args1);
     assertEqualityLinewise(m_expectedCode, toArrayOfLines(stdout));
 #endif