diff --git a/rtos/CMakeLists.txt b/rtos/CMakeLists.txt
index afecb90..f86cb83 100644
--- a/rtos/CMakeLists.txt
+++ b/rtos/CMakeLists.txt
@@ -23,7 +23,9 @@
 endif()
 
 # Include ThreadX
-if(CORE_SOFTWARE_RTOS_LOWER STREQUAL "threadx" OR CORE_SOFTWARE_RTOS_LOWER STREQUAL "all")
+# Only enable cortex-m55 until cortex-m33 is sorted out upstream
+if((CMAKE_SYSTEM_PROCESSOR STREQUAL "cortex-m55") AND
+    (CORE_SOFTWARE_RTOS_LOWER STREQUAL "threadx" OR CORE_SOFTWARE_RTOS_LOWER STREQUAL "all"))
     #threadx build requires 2 defines: THREADX_ARCH (format: cortex_m4) and THREADX_TOOLCHAIN (ac5/ac6/gnu).
     #set them according to existing defines CMAKE_SYSTEM_PROCESSOR and CMAKE_CXX_COMPILER_ID:
     string(REPLACE "-" "_" THREADX_ARCH ${CMAKE_SYSTEM_PROCESSOR})
@@ -42,4 +44,7 @@
     else()
         message(STATUS "Skipping ThreadX build - doesn't support toolchain=${THREADX_TOOLCHAIN} and cpu=${THREADX_ARCH}")
     endif()
+else()
+    message(STATUS "Disabling ThreadX for ${CMAKE_SYSTEM_PROCESSOR}, due to upstream issues")
+    # Disable cpu until upstream issue with missing files is sorted out
 endif()