diff --git a/src/lib/cdev/CDev.cpp b/src/lib/cdev/CDev.cpp
index ed668abf0e..9dc3be9cda 100644
--- a/src/lib/cdev/CDev.cpp
+++ b/src/lib/cdev/CDev.cpp
@@ -43,6 +43,10 @@
 
 #include <px4_platform_common/posix.h>
 
+#if defined(__PX4_NUTTX)
+#include <nuttx/mm/mm.h>
+#endif
+
 namespace cdev
 {
 
@@ -386,7 +390,11 @@ int CDev::unregister_driver_and_memory()
 	}
 
 	if (_devname != nullptr) {
+#if defined(__PX4_NUTTX) && !defined(CONFIG_BUILD_FLAT)
+		kmm_free((void *)_devname);
+#else
 		free((void *)_devname);
+#endif
 		_devname = nullptr;
 
 	} else {
diff --git a/src/lib/cdev/CMakeLists.txt b/src/lib/cdev/CMakeLists.txt
index 6a3f90fe9f..0d7d869fdf 100644
--- a/src/lib/cdev/CMakeLists.txt
+++ b/src/lib/cdev/CMakeLists.txt
@@ -49,7 +49,7 @@ px4_add_library(cdev
 	CDev.hpp
 	${SRCS_PLATFORM}
 )
-target_compile_options(cdev PRIVATE ${MAX_CUSTOM_OPT_LEVEL})
+target_compile_options(cdev PRIVATE ${MAX_CUSTOM_OPT_LEVEL} -D__KERNEL__)
 
 if(PX4_TESTING)
 	add_subdirectory(test)