diff --git a/libgloss/aarch64/Makefile.in b/libgloss/aarch64/Makefile.in
index 546557e3c..8111f262c 100644
--- a/libgloss/aarch64/Makefile.in
+++ b/libgloss/aarch64/Makefile.in
@@ -118,7 +118,7 @@ test:
 
 #
 crt0.o: crt0.S
-	$(CC) $(CFLAGS_FOR_TARGET) $($(MULTI_FLAGS_FOR_TARGET)) $(CFLAGS) $(INCLUDES) -o $@ -c $<
+	$(CC) $(CFLAGS_FOR_TARGET) $($(MULTI_FLAGS_FOR_TARGET)) $(CFLAGS) $(INCLUDES) -DARM_RDI_MONITOR -o $@ -c $<
 
 rdimon-crt0${${MULTILIBNAME}}.o: crt0.S
 	$(CC) $(CFLAGS_FOR_TARGET) $($(MULTI_FLAGS_FOR_TARGET)) $(CFLAGS) $(INCLUDES) -DARM_RDI_MONITOR -o $@ -c $<