diff --git a/src/experimental/platform/CMakeLists.txt b/src/experimental/platform/CMakeLists.txt
index fa0561ad..733b9ad4 100644
--- a/src/experimental/platform/CMakeLists.txt
+++ b/src/experimental/platform/CMakeLists.txt
@@ -48,6 +48,8 @@ target_sources(${MUJOCO_PLATFORM_TARGET_NAME}
         sim_history.h
         sim_profiler.cc
         sim_profiler.h
+        spec_editor.cc
+        spec_editor.h
         step_control.cc
         step_control.h
         window.cc