diff --git a/test/integration/cmake/cmake_test.go b/test/integration/cmake/cmake_test.go
index df22365..6080b6f 100644
--- a/test/integration/cmake/cmake_test.go
+++ b/test/integration/cmake/cmake_test.go
@@ -143,9 +143,31 @@ func TestCMakeProjects(t *testing.T) {
 							}
 						}
 					}
+					// Test updating for just "cpp-flat" using content from "update-cpp-flat" folder.
+					if project == "cpp-flat" {
+						t.Logf("**** Update project cpp-flat (task.fbs and main.cpp) ****")
+						cmake.CopyDir(wd, filepath.Join("update-cpp-flat", "."), filepath.Join(confDir))
+						if multiConfigBuild {
+							configs := []string{"Release", "Debug"}
+							for _, config := range configs {
+								if stdOut, stdErr, err := conf.BuildDefaultsWithConfig(config); err != nil {
+									t.Fatalf("cmake build after update (configuration %s) failed: \n%s\n%s\n%s", config, stdOut, stdErr, err)
+								} else {
+									t.Logf("build after update (configuration %s) output:\n%s", config, string(stdOut))
+								}
+							}
+						} else {
+							if stdOut, stdErr, err := conf.BuildDefaults(); err != nil {
+								t.Fatalf("cmake build after update failed: \n%s\n%s\n%s", stdOut, stdErr, err)
+							} else {
+								t.Logf("build after update output:\n%s", string(stdOut))
+							}
+						}
+					}
 				}
 			}
 		}
+
 	}
 
 	for _, singleGenerator := range singleGenerators {
@@ -155,3 +177,6 @@ func TestCMakeProjects(t *testing.T) {
 		run(multiGenerator, true)
 	}
 }
+
+func TestCMakeProjectModify(t *testing.T) {
+}
diff --git a/test/integration/cmake/update-cpp-flat/CMakeLists.txt b/test/integration/cmake/update-cpp-flat/CMakeLists.txt
new file mode 100644
index 0000000..0168825
--- /dev/null
+++ b/test/integration/cmake/update-cpp-flat/CMakeLists.txt
@@ -0,0 +1,42 @@
+cmake_minimum_required(VERSION 3.14)
+
+project(objectbox-generator-cmake-cpp-flat CXX)
+
+include(../common.cmake)
+
+add_executable(objectbox-test main.cpp)
+target_link_libraries(objectbox-test objectbox)
+
+set_target_properties(objectbox-test PROPERTIES
+    CXX_STANDARD 14
+    CXX_STANDARD_REQUIRED YES
+)
+
+# Variants:
+# - multiple add_obx_schema calls on same target
+# - single add_obx_schema call adding two schemas
+# - use OUTPUT_DIR_HEADERS (without OUTPUT_DIR)
+if (DO_INSOURCE)
+    add_obx_schema(
+        TARGET 
+            objectbox-test
+        SCHEMA_FILES 
+            task.fbs
+            monster.fbs
+            person.fbs
+        INSOURCE
+        OUTPUT_DIR_MODEL_JSON model
+        OUTPUT_DIR_HEADERS
+            include2
+    )
+    target_include_directories(objectbox-test PRIVATE include2)
+else()
+    add_obx_schema(
+        TARGET 
+            objectbox-test
+        SCHEMA_FILES 
+            task.fbs
+            monster.fbs
+            person.fbs
+    )
+endif()
diff --git a/test/integration/cmake/update-cpp-flat/main.cpp b/test/integration/cmake/update-cpp-flat/main.cpp
new file mode 100644
index 0000000..be73dd9
--- /dev/null
+++ b/test/integration/cmake/update-cpp-flat/main.cpp
@@ -0,0 +1,43 @@
+
+#define OBX_CPP_FILE
+
+
+#include "objectbox.hpp"
+
+#include "objectbox-model.h"
+#include "task.obx.hpp"
+#include "monster.obx.hpp"
+#include "person.obx.hpp"
+
+#include <cinttypes>
+
+int main(int argc, char* args[])
+{
+    // create_obx_model() provided by objectbox-model.h
+    // obx interface contents provided by objectbox.hpp
+    obx::Store store(create_obx_model());
+    obx::Box<Task> box(store);
+
+    Task my_task{};
+    my_task.text = "Buy milk";
+    obx_id id = box.put(my_task);  // Create
+
+    std::unique_ptr<Task> task = box.get(id);   // Read
+    if (task) {
+        task->text += " & some bread";
+        box.put(*task);                         // Update
+    }
+
+    printf("Your task has ID=%" PRIu64 ", text=%s\n, text2=%s\n",
+        id,
+        box.get(id)->text.c_str(),
+        box.get(id)->text2.c_str());
+    
+    obx::Box<Person> person_box(store);
+    Person my_person{};
+    obx_id person_id = person_box.put(my_person);  // Create
+    
+    printf("Your person has ID=%" PRIu64, person_id);
+
+    return 0;
+}
diff --git a/test/integration/cmake/update-cpp-flat/person.fbs b/test/integration/cmake/update-cpp-flat/person.fbs
new file mode 100644
index 0000000..07a6c45
--- /dev/null
+++ b/test/integration/cmake/update-cpp-flat/person.fbs
@@ -0,0 +1,5 @@
+table Person {
+    id: ulong;
+    name: string;
+    age: int;
+}
diff --git a/test/integration/cmake/update-cpp-flat/task.fbs b/test/integration/cmake/update-cpp-flat/task.fbs
new file mode 100644
index 0000000..df18380
--- /dev/null
+++ b/test/integration/cmake/update-cpp-flat/task.fbs
@@ -0,0 +1,7 @@
+table Task {
+    id: ulong;
+    text: string;
+    text2: string;
+    date_created: ulong;
+    date_finished: ulong;
+}