diff --git a/.gitignore b/.gitignore
index 0f873af..d94c28b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 .ccls-cache
 bin/*
 compile_commands.json
+coverage
diff --git a/Makefile b/Makefile
index 81bd0c9..9ac1951 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 MAKEFLAGS="-j $(grep -c ^processor /proc/cpuinfo)"
-CXXFLAGS=-std=c++20 -Wall -Wextra -O2 -Werror=switch
-CPPFLAGS=-Ilib/expected/ -Ilib/ut/ -Isrc/
+CXXFLAGS:=$(CXXFLAGS) -std=c++20 -Wall -Wextra -Werror=switch
+CPPFLAGS:=$(CPPFLAGS) -Ilib/expected/ -Ilib/ut/ -Isrc/
 
 Obj=bin/errors.o \
 		bin/lexer.o \
@@ -9,7 +9,6 @@ Obj=bin/errors.o \
 
 all: bin/musique bin/unit-tests
 
-
 bin/%.o: src/%.cc src/*.hh
 	g++ $(CXXFLAGS) $(CPPFLAGS) -o $@ $< -c
 
@@ -20,6 +19,14 @@ bin/musique: $(Obj) bin/main.o src/*.hh
 unit-tests: bin/unit-tests
 	./$<
 
+unit-test-coverage:
+	CXXFLAGS=--coverage $(MAKE) bin/unit-tests -B
+	bin/unit-tests
+	rm -rf coverage
+	mkdir coverage
+	gcovr -e '.*\.hpp' --html --html-details -o coverage/index.html
+	rm -rf bin
+
 bin/unit-tests: src/tests/*.cc $(Obj)
 	g++ $(CXXFLAGS) $(CPPFLAGS) -o $@ $^