diff --git a/src/lib/Makefile b/src/lib/Makefile
index 0544095..e584557 100644
--- a/src/lib/Makefile
+++ b/src/lib/Makefile
@@ -12,8 +12,8 @@ sedlexing.cma: $(MODS:.cmo=.mli) $(MODS:.cmo=.ml)
 	ocamlfind ocamlc -package gen -a -o sedlexing.cma $(MODS)

 sedlexing.cmxa: $(MODS:.cmo=.mli) $(MODS:.cmo=.ml)
-	ocamlfind ocamlopt -package gen -safe-string -c $(MODS:.cmo=.mli) $(MODS:.cmo=.ml)
-	ocamlfind ocamlopt -package gen -a -o sedlexing.cmxa $(MODS:.cmo=.cmx)
+	ocamlfind ocamlopt -g -package gen -safe-string -c $(MODS:.cmo=.mli) $(MODS:.cmo=.ml)
+	ocamlfind ocamlopt -g -package gen -a -o sedlexing.cmxa $(MODS:.cmo=.cmx)

 doc:
 	rm -rf ../../libdoc
diff --git a/src/syntax/Makefile b/src/syntax/Makefile
index ec5b86f..f5d1016 100644
--- a/src/syntax/Makefile
+++ b/src/syntax/Makefile
@@ -7,7 +7,7 @@ include $(shell ocamlc -where)/Makefile.config
 SRCS=sedlex_cset.mli sedlex_cset.ml unicode63.mli unicode63.ml sedlex.mli sedlex.ml ppx_sedlex.ml

 OCAMLC=ocamlfind ocamlc
-OCAMLOPT=ocamlfind ocamlopt
+OCAMLOPT=ocamlfind ocamlopt -g
 PACKAGES=-package ppx_tools_versioned.metaquot_405 -package ocaml-migrate-parsetree
 OCAMLFLAGS=$(PACKAGES) -linkall -w +A-4-9-42 -annot