Fortification is an important security feature.
--- a/build/cmake/aom_configure.cmake
+++ b/build/cmake/aom_configure.cmake
@@ -389,9 +389,6 @@ else()
     add_compiler_flag_if_supported("-Werror")
   endif()
 
-  if(build_type_lowercase MATCHES "rel")
-    add_compiler_flag_if_supported("-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=0")
-  endif()
   add_compiler_flag_if_supported("-D_LARGEFILE_SOURCE")
   add_compiler_flag_if_supported("-D_FILE_OFFSET_BITS=64")
 endif()