--- test/Makefile.orig	2020-01-24 15:55:37.320406491 +0200
+++ test/Makefile	2020-01-24 15:55:52.316279494 +0200
@@ -1,4 +1,4 @@
-CC = gcc
+CC ?= gcc
 
 CFLAGS = -std=gnu99 -Wall -DFAKE_STAT -Werror -Wextra $(FAKETIME_COMPILE_CFLAGS)
 LDFLAGS = -lrt -lpthread

--- test/Makefile.orig	2020-01-24 16:06:25.858716206 +0200
+++ test/Makefile	2020-01-24 16:06:52.438470272 +0200
@@ -1,7 +1,7 @@
-CC = gcc
+CC ?= gcc
 
-CFLAGS = -std=gnu99 -Wall -DFAKE_STAT -Werror -Wextra $(FAKETIME_COMPILE_CFLAGS)
-LDFLAGS = -lrt -lpthread
+CFLAGS = $(CFLAGS) -std=gnu99 -Wall -DFAKE_STAT -Werror -Wextra $(FAKETIME_COMPILE_CFLAGS)
+LDFLAGS = $(LDFLAGS) -lrt -lpthread
 
 SRC = timetest.c
 OBJ = ${SRC:.c=.o}

Add possibility to add to CFLAGS / LDFLAGS
Add possibility to add to CFLAGS / LDFLAGS
