diff --git a/include/aout/ChangeLog b/include/aout/ChangeLog
index 63f17ec830..1645a5ac70 100644
--- a/include/aout/ChangeLog
+++ b/include/aout/ChangeLog
@@ -1,3 +1,12 @@
+Mon Apr  3 13:29:08 2000  Hans-Peter Nilsson  <hp@axis.com>
+
+	* aout64.h (RELOC_EXT_BITS_EXTERN_BIG): Wrap definition in #ifndef.
+	(RELOC_EXT_BITS_EXTERN_LITTLE): Ditto.
+	(RELOC_EXT_BITS_TYPE_BIG): Ditto.
+	(RELOC_EXT_BITS_TYPE_SH_BIG): Ditto.
+	(RELOC_EXT_BITS_TYPE_LITTLE): Ditto.
+	(RELOC_EXT_BITS_TYPE_SH_LITTLE): Ditto.
+
 1999-07-12  Ian Lance Taylor  <ian@zembu.com>
 
 	* aout64.h (N_SHARED_LIB): Define as 0 if TEXT_START_ADDR is
diff --git a/include/aout/aout64.h b/include/aout/aout64.h
index bf743c4866..bec8440364 100644
--- a/include/aout/aout64.h
+++ b/include/aout/aout64.h
@@ -388,13 +388,29 @@ struct reloc_ext_external {
   bfd_byte r_addend[BYTES_IN_WORD];	/* datum addend				*/
 };
 
+#ifndef RELOC_EXT_BITS_EXTERN_BIG
 #define	RELOC_EXT_BITS_EXTERN_BIG	((unsigned int) 0x80)
-#define	RELOC_EXT_BITS_EXTERN_LITTLE	((unsigned int) 0x01)
+#endif
 
+#ifndef RELOC_EXT_BITS_EXTERN_LITTLE
+#define	RELOC_EXT_BITS_EXTERN_LITTLE	((unsigned int) 0x01)
+#endif
+
+#ifndef RELOC_EXT_BITS_TYPE_BIG
 #define	RELOC_EXT_BITS_TYPE_BIG		((unsigned int) 0x1F)
+#endif
+
+#ifndef RELOC_EXT_BITS_TYPE_SH_BIG
 #define	RELOC_EXT_BITS_TYPE_SH_BIG	0
+#endif
+
+#ifndef RELOC_EXT_BITS_TYPE_LITTLE
 #define	RELOC_EXT_BITS_TYPE_LITTLE	((unsigned int) 0xF8)
+#endif
+
+#ifndef RELOC_EXT_BITS_TYPE_SH_LITTLE
 #define	RELOC_EXT_BITS_TYPE_SH_LITTLE	3
+#endif
 
 /* Bytes per relocation entry */
 #define	RELOC_EXT_SIZE	(BYTES_IN_WORD + 3 + 1 + BYTES_IN_WORD)