diff -up rpc2-2.10/rp2gen/Makefile.am.cflags rpc2-2.10/rp2gen/Makefile.am
--- rpc2-2.10/rp2gen/Makefile.am.cflags	2020-08-10 14:41:30.664876095 -0400
+++ rpc2-2.10/rp2gen/Makefile.am	2020-08-10 14:41:44.903843414 -0400
@@ -6,7 +6,7 @@ AM_YFLAGS= -d
 INCLUDES = -I$(top_builddir)/include -I$(top_srcdir)/include -I$(srcdir) -I.
 
 .c.o:
-	$(NATIVECC) $(INCLUDES) -c $<
+	$(NATIVECC) $(CFLAGS) $(INCLUDES) -c $<
 
 bin_PROGRAMS = rp2gen
 
diff -up rpc2-2.10/rp2gen/Makefile.in.cflags rpc2-2.10/rp2gen/Makefile.in
--- rpc2-2.10/rp2gen/Makefile.in.cflags	2020-08-10 14:42:35.839726505 -0400
+++ rpc2-2.10/rp2gen/Makefile.in	2020-08-10 14:42:44.687706199 -0400
@@ -556,7 +556,7 @@ uninstall-am: uninstall-binPROGRAMS
 
 
 .c.o:
-	$(NATIVECC) $(INCLUDES) -c $<
+	$(NATIVECC) $(CFLAGS) $(INCLUDES) -c $<
 
 rp2gen_parser.h: rp2gen_parser.c
 rp2gen_lexer.c: rp2gen_parser.h