diff -u a/Makefile b/Makefile
--- a/Makefile
+++ b/Makefile
@@ -1,1 +1,5 @@
-TARGETS = opam-file-format.cma opam-file-format.cmxa opam-file-format.cmxs
+TARGETS = opam-file-format.cma opam-file-format.cmxa
+
+ifeq "$(NATDYNLINK)" "true"
+TARGETS = $(TARGETS) opam-file-format.cmxs
+endif

all: $(TARGETS)