diff --git a/configure/CONFIG_COMMON b/configure/CONFIG_COMMON
index 692c46688..e5205b60f 100644
--- a/configure/CONFIG_COMMON
+++ b/configure/CONFIG_COMMON
@@ -289,6 +289,12 @@ ARCMD = $(AR) $(ARFLAGS) $(USR_ARFLAGS) $@  $(LIBRARY_LD_OBJS)
 # 'Munch' link-edit
 MUNCH_CMD = $(LD) -o $@ $^
 
+#--------------------------------------------------
+# LEX default option (valid for EPICS base 3.13.0.beta12 and later)
+#
+# to allow characters that are not plain 7bit standard ASCII 
+LEXOPT +=  -8
+
 #--------------------------------------------------
 # Build compile line here