diff --git a/harbour/config/c.cf b/harbour/config/c.cf
index 85d94a9110..a615188ef4 100644
--- a/harbour/config/c.cf
+++ b/harbour/config/c.cf
@@ -8,6 +8,10 @@ C_MAIN_OBJ = $(C_MAIN:.c=$(OBJ_EXT))
 
 ifdef YACC_SOURCE
 YACC_BASE = $(YACC_SOURCE:.y=)
+#must be harbour.sly
+ifeq ($(YACC_BASE),$(YACC_SOURCE))
+YACC_BASE = $(YACC_SOURCE:.sly=)
+endif
 YACC_C = $(YACC_BASE)y.c
 YACC_H_TMP = $(YACC_C:.c=.h)
 YACC_H = y_tab.h
diff --git a/harbour/source/compiler/Makefile b/harbour/source/compiler/Makefile
index c2ade0a077..dfa52cb93d 100644
--- a/harbour/source/compiler/Makefile
+++ b/harbour/source/compiler/Makefile
@@ -4,8 +4,16 @@
 
 ROOT = ../../
 
+ifeq ($(HB_LEX),SIMPLEX)
+
+YACC_SOURCE=harbour.sly
+
+else
+
 YACC_SOURCE=harbour.y
 
+endif
+
 YACC_HEADERS=\
 	hbcomp.h \
 	hbsetup.h \