diff --git a/.gitpod.yml b/.gitpod.yml
index 550e9cd..909c6cf 100644
--- a/.gitpod.yml
+++ b/.gitpod.yml
@@ -2,11 +2,8 @@ image:
   file: Dockerfile
 tasks:
 - command: >
-    mkdir --parents build &&
-    cd build &&
-    cmake .. &&
-    make &&
-    ./tinykaboom &&
+    cmake -Bbuild &&
+    cmake --build build &&
+    build/tinykaboom &&
     pnmtopng out.ppm > out.png &&
-    open out.png &&
-    cd ..
+    open out.png
diff --git a/CMakeLists.txt b/CMakeLists.txt
index de86bd7..f9aca84 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,27 +1,24 @@
-cmake_minimum_required (VERSION 2.8)
-project (tinykaboom)
-
-include(CheckCXXCompilerFlag)
-
-function(enable_cxx_compiler_flag_if_supported flag)
-    string(FIND "${CMAKE_CXX_FLAGS}" "${flag}" flag_already_set)
-    if(flag_already_set EQUAL -1)
-        check_cxx_compiler_flag("${flag}" flag_supported)
-        if(flag_supported)
-            set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${flag}" PARENT_SCOPE)
-        endif()
-        unset(flag_supported CACHE)
-    endif()
-endfunction()
-
-enable_cxx_compiler_flag_if_supported("-Wall")
-enable_cxx_compiler_flag_if_supported("-Wextra")
-enable_cxx_compiler_flag_if_supported("-pedantic")
-enable_cxx_compiler_flag_if_supported("-std=c++11")
-enable_cxx_compiler_flag_if_supported("-O3")
-enable_cxx_compiler_flag_if_supported("-fopenmp")
-
-file(GLOB SOURCES *.h *.cpp)
+cmake_minimum_required(VERSION 3.10...3.26)
+
+get_property(is_multi_config GLOBAL PROPERTY GENERATOR_IS_MULTI_CONFIG)
+if(NOT is_multi_config AND NOT (CMAKE_BUILD_TYPE OR DEFINED ENV{CMAKE_BUILD_TYPE}))
+  set(CMAKE_BUILD_TYPE Release CACHE STRING "Release default")
+endif()
+
+project(tinykaboom LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+if(CMAKE_CXX_COMPILER_ID MATCHES "Clang|GNU|Intel")
+  add_compile_options(-Wall -Wextra -Wpedantic)
+endif()
+
+find_package(OpenMP COMPONENTS CXX)
+
+set(SOURCES tinykaboom.cpp)
 
 add_executable(${PROJECT_NAME} ${SOURCES})
+target_link_libraries(${PROJECT_NAME} PRIVATE $<$<BOOL:${OpenMP_CXX_FOUND}>:OpenMP::OpenMP_CXX>)
 
+file(GENERATE OUTPUT .gitignore CONTENT "*")
diff --git a/Readme.md b/Readme.md
index c39522a..631bdd1 100644
--- a/Readme.md
+++ b/Readme.md
@@ -10,13 +10,13 @@ In my lectures I tend to avoid third party libraries as long as it is reasonable
 ![](https://raw.githubusercontent.com/ssloy/tinykaboom/master/out.jpg)
 
 ## compilation
+
 ```sh
 git clone https://github.com/ssloy/tinykaboom.git
 cd tinykaboom
-mkdir build
-cd build
-cmake ..
-make
+cmake -Bbuild
+cmake --build build
+build/tinykaboom
 ```
 
 You can open the project in Gitpod, a free online dev evironment for GitHub:
@@ -27,7 +27,7 @@ On open, the editor will compile & run the program as well as open the resulting
 Just change the code in the editor and rerun the script (use the terminal's history) to see updated images.
 
 ## Homework
-The possibilities are infinte. For example, you can add the environment map and some transparency:  
+The possibilities are infinte. For example, you can add the environment map and some transparency:
 ![](https://raw.githubusercontent.com/ssloy/tinykaboom/homework_assignment/envmap1.jpg)
 
 Add other objects and illuminate them:
diff --git a/tinykaboom.cpp b/tinykaboom.cpp
index ab7d904..94fc5c2 100644
--- a/tinykaboom.cpp
+++ b/tinykaboom.cpp
@@ -96,7 +96,7 @@ int main() {
     std::vector<Vec3f> framebuffer(width*height);
 
 #pragma omp parallel for
-    for (size_t j = 0; j<height; j++) { // actual rendering loop
+    for (int j = 0; j<height; j++) { // actual rendering loop
         for (size_t i = 0; i<width; i++) {
             float dir_x =  (i + 0.5) -  width/2.;
             float dir_y = -(j + 0.5) + height/2.;    // this flips the image at the same time
@@ -124,4 +124,3 @@ int main() {
 
     return 0;
 }
-