diff --git a/Rules.mak b/Rules.mak
index 537c3967c..b3ebeac1f 100644
--- a/Rules.mak
+++ b/Rules.mak
@@ -77,11 +77,11 @@ CFLAGS_EXTRA=$(subst ",, $(strip $(EXTRA_CFLAGS_OPTIONS)))
 # For other libraries, you are on your own.  But these may (or may not) help...
 #LDFLAGS+=-nostdlib
 #LIBRARIES:=$(LIBCDIR)/lib/libc.a -lgcc
-#CROSS_CFLAGS+=-nostdinc -I$(LIBCDIR)/include -I$(GCCINCDIR)
+#CROSS_CFLAGS+=-nostdinc -I$(LIBCDIR)/include -I$(GCCINCDIR) -funsigned-char
 #GCCINCDIR:=$(shell gcc -print-search-dirs | sed -ne "s/install: \(.*\)/\1include/gp")
 
 WARNINGS=-Wall -Wstrict-prototypes -Wshadow
-CFLAGS=-I$(top_builddir)/include -I$(top_srcdir)/include -I$(srcdir)
+CFLAGS=-I$(top_builddir)/include -I$(top_srcdir)/include -I$(srcdir) -funsigned-char
 ARFLAGS=cru
 
 #--------------------------------------------------------