diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9a1f7d1a..4a1ec8c4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -38,7 +38,7 @@ elseif(${CMAKE_CXX_STANDARD} LESS 11)
 endif()
 
 # Backwards comptability
-if(OS_FSFW)
+if(OS_FSFW AND NOT FSFW_OSAL)
     message(WARNING "Please pass the FSFW OSAL as FSFW_OSAL instead of OS_FSFW")
     set(FSFW_OSAL OS_FSFW)
 endif()