diff --git a/doc/Makefile.am b/doc/Makefile.am
index 999e5c2aa7..ebde944986 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -43,7 +43,7 @@ html-local: stamp-html stamp-man
 install-data-local:
 	$(MKDIR_P) $(DESTDIR)$(docdir); \
 	for dir in $(DOCDIRS); do \
-	  cp -nrf $$dir $(DESTDIR)$(docdir); \
+	  cp -fpR $$dir $(DESTDIR)$(docdir); \
 	done
 
 uninstall-local: