diff --git a/Makefile b/Makefile
index ced0f39..0c32e25 100644
--- a/Makefile
+++ b/Makefile
@@ -19,11 +19,11 @@ MAKEFLAGS += --no-print-directory
 
 include sources.mk
 
-CC = clang
-CPPFLAGS = -std=c99 -I includes -D_POSIX_C_SOURCE=199309L
-CFLAGS = -Wall -Wextra -Werror -pipe -Wpedantic -Wconversion
+CC ?= clang
+CPPFLAGS ?= -std=c99 -I includes -D_POSIX_C_SOURCE=199309L
+CFLAGS ?= -Wall -Wextra -Werror -pipe -Wpedantic -Wconversion
 CFLAGS_SHARED = $(CFLAGS) -fPIC
-LDFLAGS =
+LDFLAGS ?=
 TEST_LDFLAGS = -lcriterion
 TEST_CFLAGS = -Wall -Wextra -Werror -pipe