Use preserve mode to copy headers.
diff --git a/Makefile b/Makefile index a0fcb2b..78c1acb 100644 --- a/Makefile +++ b/Makefile
@@ -23,7 +23,7 @@ ifndef WINDOWS install: no_test mkdir -p $(DESTDIR)/include/mbedtls - cp -r include/mbedtls $(DESTDIR)/include + cp -rp include/mbedtls $(DESTDIR)/include mkdir -p $(DESTDIR)/lib cp -RP library/libmbedtls.* $(DESTDIR)/lib