diff --git a/doc/ceg/Makefile b/doc/ceg/Makefile
index 37a65b7fb..4a66a1f62 100644
--- a/doc/ceg/Makefile
+++ b/doc/ceg/Makefile
@@ -1,6 +1,7 @@
 PIC=pic
 TBL=tbl
 TARGET=-Tlp
+REFER=refer
 
 ../ceg.doc:	ceg.tr ceg.ref
-	$(PIC) $(TARGET) ceg.tr | refer -e -p ceg.ref | $(TBL) > $@
+	$(PIC) $(TARGET) ceg.tr | $(REFER) -e -p ceg.ref | $(TBL) > $@