--- GNUmakefile.orig	2022-01-17 21:45:51 UTC
+++ GNUmakefile
@@ -24,7 +24,7 @@ install: install-html install-include install-examples
 # recursively copy include/Random123 to $(includedir)
 install-include:
 	mkdir -p $(DESTDIR)$(includedir)
-	cp -dr include/Random123 $(DESTDIR)$(includedir)
+	cp -r include/Random123 $(DESTDIR)$(includedir)
 .PHONY: install-include
 
 # docs/main.md is the same as README.md, but it has a @mainpage