diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 52352601..e6ee390f 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -20,5 +20,15 @@ jobs:
         sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-10 10
     - name: Build and unit test
       run: |
-        NUMPROC=2 make debug
+        NUMPROC=2 CMAKE_CXX_FLAGS="--coverage -fno-inline" make debug
         make test
+    - name: Run coverage
+      run: |
+        lcov --no-external --directory src -c -d debug -o coverage.info
+        lcov -l coverage.info
+    - name: Upload coverage
+      uses: codecov/codecov-action@v2
+      with:
+        files: coverage.info
+        name: clang-uml
+        fail_ci_if_error: true
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index b474bd93..cb62a1b3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,6 +20,8 @@ bin/
 /.cache
 docs/diagrams
 
+coverage.info
+
 
 # CLion
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0dd72aca..912da58a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -47,6 +47,7 @@ set(LLVM_PREFERRED_VERSION 12.0.0)
 find_package(LibClang REQUIRED)
 
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++17 ${LIBCLANG_CXXFLAGS}")
+message(STATUS "Using CMAKE_CXX_FLAGS: ${CMAKE_CXX_FLAGS}")
 
 # Thirdparty sources
 set(THIRDPARTY_HEADERS_DIR ${PROJECT_SOURCE_DIR}/thirdparty/)
diff --git a/Makefile b/Makefile
index 1eebfe73..09933fdb 100644
--- a/Makefile
+++ b/Makefile
@@ -23,6 +23,7 @@
 NUMPROC ?= $(shell nproc)
 
 LLVM_CONFIG_PATH ?=
+CMAKE_CXX_FLAGS ?=
 
 .PHONY: clean
 clean:
@@ -32,6 +33,7 @@ debug/CMakeLists.txt:
 	cmake -S . -B debug \
 		-DCMAKE_CXX_COMPILER_LAUNCHER=ccache \
 		-DCMAKE_BUILD_TYPE=Debug \
+		-DCMAKE_CXX_FLAGS="$(CMAKE_CXX_FLAGS)" \
 		-DLLVM_CONFIG_PATH=$(LLVM_CONFIG_PATH)
 
 release/CMakeLists.txt:
diff --git a/README.md b/README.md
index 901341ba..5eda7cba 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # clang-uml - C++ UML diagram generator based on Clang and PlantUML
 
-![linux build](https://github.com/bkryza/clang-uml/actions/workflows/build.yml/badge.svg)
+[![Build status]](https://github.com/bkryza/clang-uml/actions/workflows/build.yml/badge.svg)
+[![Coverage](https://codecov.io/gh/bkryza/clang-uml/branch/master/graph/badge.svg)](https://codecov.io/gh/bkryza/clang-uml)
 
 `clang-uml` is an automatic C++ to [PlantUML](https://plantuml.com) class, sequence
 and package diagram generator, driven by YAML configuration files. The main idea behind the