Index: Makefile
===================================================================
--- Makefile	(revision 55edaf30bf5443215a1e66ace86cb56aab83c1f2)
+++ Makefile	(revision ff9ab1a3eb065857e129dc1be6d44da27e1985a2)
@@ -19,4 +19,9 @@
 				-Wstrict-prototypes -Wmissing-declarations -Wredundant-decls \
 				-I include
+
+# the assembly code doesn't preserve registers d2 and a2; don't use them
+# until this is fixed
+
+FLAGS_COM +=	-ffixed-d2 -ffixed-a2
 
 FLAGS_ASM :=	$(FLAGS) -Wa,--register-prefix-optional,--base-size-default-16