diff --git a/iopsys-econet/rule.mak b/iopsys-econet/rule.mak
index 5543d2930dc0945930c8bc73be92c03b7188a66d..296117680421b5606b90c8a76a83aa12daa25708 100644
--- a/iopsys-econet/rule.mak
+++ b/iopsys-econet/rule.mak
@@ -816,6 +816,8 @@ export COMPILE_TOOLCHAIN
 export ALIAS_TOOLCHAIN
 else
 COMPILE_TOOLCHAIN=$(ARCH)-openwrt-linux-$(TARGET_SUFFIX)-gcc
+BSP_CFLAGS+=-fsigned-char
+EXTRA_CFLAGS+=-fsigned-char
 export COMPILE_TOOLCHAIN
 endif