diff --git a/gcc/config/rs6000/lynx.h b/gcc/config/rs6000/lynx.h
index 3434c8b3989c7114807a9f7a790ed6ef3fac5698..0ddb54f213e801ae40a52ca31b003ce67321a7e9 100644
--- a/gcc/config/rs6000/lynx.h
+++ b/gcc/config/rs6000/lynx.h
@@ -80,7 +80,6 @@
 
 #undef SIZE_TYPE
 #undef ASM_OUTPUT_ALIGN
-#undef PREFERRED_DEBUGGING_TYPE
 
 /* The file rs6000.c defines TARGET_HAVE_TLS unconditionally to the
    value of HAVE_AS_TLS.  HAVE_AS_TLS is true as gas support for TLS