diff --git a/gnu/usr.bin/binutils/as/Makefile b/gnu/usr.bin/binutils/as/Makefile
index 9bf4880faf2..a5473a77e9b 100644
--- a/gnu/usr.bin/binutils/as/Makefile
+++ b/gnu/usr.bin/binutils/as/Makefile
@@ -35,6 +35,9 @@ CFLAGS+= -DDEFAULT_ARCH=\"v9-64\"
 .else
 CFLAGS+= -DDEFAULT_ARCH=\"${BINUTILS_ARCH}\"
 .endif
+.if defined(TARGET_BIG_ENDIAN)
+CFLAGS+= -DTARGET_BYTES_BIG_ENDIAN=1
+.endif
 CFLAGS+= -DTARGET_CPU=\"${BINUTILS_ARCH}\"
 CFLAGS+= -DTARGET_CANONICAL=\"${TARGET_TUPLE}\"
 CFLAGS+= -DTARGET_ALIAS=\"${TARGET_TUPLE}\"