diff -u -r ../tty-solitaire-1.0.0/Makefile ./Makefile
--- ../tty-solitaire-1.0.0/Makefile	2017-01-07 23:39:19.000000000 +0100
+++ ./Makefile	2017-09-23 01:38:01.226934201 +0200
@@ -1,14 +1,14 @@
-CC     = gcc
-CFLAGS = -W -Wall -pedantic -ansi -std=c99 -g
+CC     ?= gcc
+CFLAGS ?= -W -Wall -pedantic -ansi -std=c99 -g
 
-LDFLAGS = -lncursesw
+LDFLAGS += -lncursesw
 
 # OS X installs ncurses with wide character support, but not as "libncurses"
 ifeq ($(shell uname -s),Darwin)
 	LDFLAGS = -lncurses
 endif
 
-PREFIX  = /usr/local
+PREFIX  ?= /usr/local
 
 EXECUTABLE = ttysolitaire
 SRC_DIR    = src
@@ -40,7 +40,7 @@
 .PHONY: test clean install uninstall
 
 ttysolitaire: $(SRC_OBJECTS)
-	$(CC) $(CFLAGS) $(SRC) -o $(EXECUTABLE) $(SRC_OBJECTS) $(LDFLAGS)
+	$(CC) $(CFLAGS) $(CPPFLAGS) $(SRC) -o $(EXECUTABLE) $(SRC_OBJECTS) $(LDFLAGS)
 
 test: $(SRC_OBJECTS) $(TESTS_OBJECTS)
 	@$(CC) $(CFLAGS) $(TESTS_SRC) -o $(TESTS_EXECUTABLE) $(TESTS_OBJECTS) $(SRC_OBJECTS) $(LDFLAGS)