diff --git a/Makefile b/Makefile
index b03d94f..23f9b5b 100644
--- a/Makefile
+++ b/Makefile
@@ -33,9 +33,17 @@ else # GNU/Linux, at least (Windows should probably use cmake)
 endif
 
 # installation directories (for 'make install')
-prefix=/usr/local
-libdir=$(prefix)/lib
-includedir=$(prefix)/include
+DESTDIR     ?=
+# directory variables : GNU conventions prefer lowercase
+# see https://www.gnu.org/prep/standards/html_node/Makefile-Conventions.html
+# support both lower and uppercase (BSD), use uppercase in script
+prefix      ?= /usr/local
+PREFIX      ?= $(prefix)
+exec_prefix ?= $(PREFIX)
+libdir      ?= $(exec_prefix)/lib
+LIBDIR      ?= $(libdir)
+includedir  ?= $(PREFIX)/include
+INCLUDEDIR  ?= $(includedir)
 
 # meta targets
 
diff --git a/README.md b/README.md
index 247c7b1..219cef2 100644
--- a/README.md
+++ b/README.md
@@ -30,9 +30,21 @@ data governed by the similarly permissive [Unicode data
 license](http://www.unicode.org/copyright.html#Exhibit1)); please see
 the included `LICENSE.md` file for more detailed information.
 
-## Quick Start
+## Installation
 
-For compilation of the C library run `make`.
+```
+make            # compilation of the C library
+make install    # this command may require root access
+```
+
+utf8proc's `Makefile` supports standard [Makefile conventions],
+including [staged installs], [redirection], or [command redefinition].
+It is compatible with parallel builds (`-j#`).
+
+[Makefile conventions]: https://www.gnu.org/prep/standards/html_node/Makefile-Conventions.html
+[staged installs]: https://www.gnu.org/prep/standards/html_node/DESTDIR.html
+[redirection]: https://www.gnu.org/prep/standards/html_node/Directory-Variables.html
+[command redefinition]: https://www.gnu.org/prep/standards/html_node/Utilities-in-Makefiles.html
 
 ## General Information