diff --git a/Makefile b/Makefile
index 94174b6..b604f6a 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,5 @@
+MAKEFLAGS += --warn-undefined-variables
+
 install_path    = /usr/local/bin
 links_path      = ~/.shellrc/bin/scripts
 local_man_path  = ~/.shellrc/var/man/man1
@@ -14,10 +16,11 @@ MAN_FILES := $(addsuffix ".1", $(MAN_PAGES))
 
 # --------------------------------------------------------------------------------------------------
 
-# copy_files [FILES] TO/
-define copy_files
+# install_files [FILES] TO/
+define install_files
 	@for file in $(1); do \
-		cp -v $$(realpath -- $$file) $(2)/$$(basename $$file); \
+		echo install -m $(3) $$(realpath -- $$file) $(2)/$$(basename $$file); \
+		install -m $(3) $$(realpath -- $$file) $(2)/$$(basename $$file); \
 	done
 endef
 
@@ -69,13 +72,13 @@ make_man_directory:
 	@mkdir -p $(system_man_path)
 
 copy_bin:
-	$(call copy_files, $(SCRIPTS), $(install_path))
+	$(call install_files, $(SCRIPTS), $(install_path), 755)
 
 rm_bin:
 	$(call delete_files, $(SCRIPTS), $(install_path))
 
 copy_man_pages: make_man_directory
-	$(call copy_files, $(MAN_FILES), $(system_man_path))
+	$(call install_files, $(MAN_FILES), $(system_man_path), 644)
 
 rm_man_pages: make_man_directory
 	$(call delete_files, $(MAN_FILES), $(system_man_path))