diff --git a/toolchain_GNUARM.cmake b/toolchain_GNUARM.cmake
index e100ab6..067101d 100644
--- a/toolchain_GNUARM.cmake
+++ b/toolchain_GNUARM.cmake
@@ -124,6 +124,7 @@
         set_source_files_properties(${SCATTER_FILE_PATH}
             PROPERTIES
             LANGUAGE C
+            KEEP_EXTENSION True # Don't use .o extension for the preprocessed file
         )
     endforeach()
 
@@ -273,4 +274,4 @@
                             ${ORIG_TARGET}
                             "${LIB_LIST}"
     )
-endmacro()
\ No newline at end of file
+endmacro()