diff --git a/src/libCom/as/RULES b/src/libCom/as/RULES
index 3ec90b630..5ed3edd97 100644
--- a/src/libCom/as/RULES
+++ b/src/libCom/as/RULES
@@ -17,3 +17,4 @@ asLib$(DEP): asLib_lex.c
 # Ensure that lexer and parser are built before they are needed
 asLib.c: $(call PATH_FILTER, $(TOOLS)/antelope$(HOSTEXE))
 asLib_lex.c: $(call PATH_FILTER, $(TOOLS)/e_flex$(HOSTEXE))
+asLib_lex.c: $(INSTALL_INCLUDE)/flex.skel.static