diff --git a/CMakeLists.txt b/CMakeLists.txt
index adc7ebb..f3cfff7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -34,6 +34,7 @@ enable_testing()
 find_package(Catch2 REQUIRED)
 add_executable(UnitTests ${SOURCES} ${HEADERS} ${TESTS})
 target_link_libraries(UnitTests Catch2::Catch2)
+target_link_libraries(UnitTests ${LIB_PATH}/lib/liblibrary.a)
 
 include(CTest)
 include(Catch)
diff --git a/src/DrawRender.cpp b/src/DrawRender.cpp
index 435a0ec..1d71731 100644
--- a/src/DrawRender.cpp
+++ b/src/DrawRender.cpp
@@ -1,4 +1,3 @@
-#include "Color.hpp"
 #include "DrawRender.hpp"
 #include "vkvm.hpp"
 #include <algorithm>
@@ -28,7 +27,7 @@ void DrawRender::graphicsUpdate(int type) {
 
         if(center.x + radius > windowWidth || center.x - radius < 0
                 || center.y + radius > windowHeight || center.y - radius < 0) {
-            radius = utils::min(utils::min(center.x, windowWidth - center.x), utils::min(center.y, windowHeight - center.y));
+            radius = std::min(std::min(center.x, windowWidth - center.x), std::min(center.y, windowHeight - center.y));
         }
 
         oldCircle = Circle(center, radius, penWidth, false);
diff --git a/src/Rectangle.cpp b/src/Rectangle.cpp
index cf5f18b..b136560 100644
--- a/src/Rectangle.cpp
+++ b/src/Rectangle.cpp
@@ -17,10 +17,10 @@ Rectangle::Rectangle(vkvm::Coordinates mouseLeftDownPostion, vkvm::Coordinates m
 
     length = abs(mouseLeftDownPosition.x - mousePosition.x);
     width = abs(mouseLeftDownPosition.y - mousePosition.y);
-    uperLeft.x = utils::min(mouseLeftDownPosition.x, mousePosition.x);
-    uperLeft.y = utils::min(mouseLeftDownPosition.y, mousePosition.y);
-    bottomRight.x = utils::max(mouseLeftDownPosition.x, mousePosition.x);
-    bottomRight.y = utils::max(mouseLeftDownPosition.y, mousePosition.y);
+    uperLeft.x = std::min(mouseLeftDownPosition.x, mousePosition.x);
+    uperLeft.y = std::min(mouseLeftDownPosition.y, mousePosition.y);
+    bottomRight.x = std::max(mouseLeftDownPosition.x, mousePosition.x);
+    bottomRight.y = std::max(mouseLeftDownPosition.y, mousePosition.y);
 
     rectangle.resize(width);
     for(y_draw = 0; y_draw < width; y_draw++) {
diff --git a/src/utils.cpp b/src/utils.cpp
index 9fb3201..0c63ccb 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -1,7 +1,3 @@
-//
-// Created by shaohuatong on 06.12.19.
-//
-
 #include "utils.hpp"
 
 int utils::squareOfDistance(vkvm::Coordinates x, vkvm::Coordinates y) {
@@ -10,16 +6,4 @@ int utils::squareOfDistance(vkvm::Coordinates x, vkvm::Coordinates y) {
 
 int utils::getDistance(vkvm::Coordinates x, vkvm::Coordinates y) {
     return (int)floor(sqrt(squareOfDistance(x, y)));
-}
-
-int utils::min(int x, int y) {
-    if(x <= y)
-        return x;
-    return y;
-}
-
-int utils::max(int x, int y) {
-    if(x<=y)
-        return y;
-    return x;
 }
\ No newline at end of file
diff --git a/src/utils.hpp b/src/utils.hpp
index c208db5..fd9c082 100644
--- a/src/utils.hpp
+++ b/src/utils.hpp
@@ -6,15 +6,12 @@
 #define SIMPLE_DRAW_UTILS_HPP
 
 #include "vkvm.hpp"
-#include "internal.hpp"
-#include "math.h"
+#include <cmath>
 
 class utils {
 public:
     static int squareOfDistance(vkvm::Coordinates x, vkvm::Coordinates y);
     static int getDistance(vkvm::Coordinates x, vkvm::Coordinates y);
-    static int min(int x, int y);
-    static int max(int x, int y);
 };