diff --git a/lib/CamlPaml/Makefile b/lib/CamlPaml/Makefile
index 396c917..d913d87 100644
--- a/lib/CamlPaml/Makefile
+++ b/lib/CamlPaml/Makefile
@@ -1,10 +1,10 @@
 LIBNAME = CamlPaml
 
 lib:
-	ocamlbuild -use-ocamlfind ${LIBNAME}.cma ${LIBNAME}.cmxa
+	ocamlbuild -cflag '-unsafe-string' -use-ocamlfind ${LIBNAME}.cma ${LIBNAME}.cmxa
 
 test:
-	ocamlbuild -use-ocamlfind test.native
+	ocamlbuild -cflag '-unsafe-string' -use-ocamlfind test.native
 	_build/test.native
 
 
@@ -20,7 +20,7 @@ reinstall:
 
 clean:
 	rm -f *~
-	ocamlbuild -clean
+	ocamlbuild -cflag '-unsafe-string' -clean
 
 doc:
-	ocamlbuild -use-ocamlfind ${LIBNAME}.docdir/index.html
+	ocamlbuild -cflag '-unsafe-string' -use-ocamlfind ${LIBNAME}.docdir/index.html
diff --git a/src/Makefile b/src/Makefile
index 7ab37f8..db47e8a 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -10,16 +10,16 @@ ifdef FORKWORK
 else
 	ln -s ForkNo.ml ForkMaybe.ml
 endif
-	ocamlbuild -use-ocamlfind $(OCAMLBUILDFLAGS) PhyloCSF.native
+	ocamlbuild -cflag '-unsafe-string' -use-ocamlfind $(OCAMLBUILDFLAGS) PhyloCSF.native
 
 test: testexe
 	./test.native -verbose
 
 testexe: all
-	ocamlbuild -use-ocamlfind $(OCAMLBUILDFLAGS) testSim.native test.native
+	ocamlbuild -cflag '-unsafe-string' -use-ocamlfind $(OCAMLBUILDFLAGS) testSim.native test.native
 
 clean:
 	rm -f *~
-	ocamlbuild -clean
+	ocamlbuild -cflag '-unsafe-string' -clean
 
 .PHONY: all test testexe clean