diff --git a/QT/bezier_1/mywindow.cpp b/QT/bezier_1/mywindow.cpp
index a82ca7b..5b84fb8 100644
--- a/QT/bezier_1/mywindow.cpp
+++ b/QT/bezier_1/mywindow.cpp
@@ -240,7 +240,7 @@ void MyWindow::DrawLine(int x1, int y1, int x2, int y2, QImage *img){
 
     QColor color(255, 255, 255, 255);
 
-    if(abs(a) < 0.5f){
+    if(abs(a) < 1.0f){
         for(int x = x1; x <= x2; x++){
             int x_form = x - x1;
             int y = a * x_form + y1;
diff --git a/QT/bezier_2/mywindow.cpp b/QT/bezier_2/mywindow.cpp
index 628f9e6..eddaf66 100644
--- a/QT/bezier_2/mywindow.cpp
+++ b/QT/bezier_2/mywindow.cpp
@@ -226,7 +226,7 @@ void MyWindow::DrawLine(int x1, int y1, int x2, int y2, QImage *img){
 
     QColor color(255, 255, 255, 255);
 
-    if(abs(a) < 0.5f){
+    if(abs(a) < 1.0f){
         for(int x = x1; x <= x2; x++){
             int x_form = x - x1;
             int y = a * x_form + y1;
diff --git a/QT/kolo/mywindow.cpp b/QT/kolo/mywindow.cpp
index 98532b2..0acba6d 100644
--- a/QT/kolo/mywindow.cpp
+++ b/QT/kolo/mywindow.cpp
@@ -236,7 +236,7 @@ void MyWindow::DrawLine(int x1, int y1, int x2, int y2, bool update_temp){
 
     QColor color(255, 255, 255, 255);
 
-    if(abs(a) < 0.5f){
+    if(abs(a) < 1.0f){
         for(int x = x1; x <= x2; x++){
             int x_form = x - x1;
             int y = a * x_form + y1;
diff --git a/QT/scan-line/mywindow.cpp b/QT/scan-line/mywindow.cpp
index 9a2be79..20263e6 100644
--- a/QT/scan-line/mywindow.cpp
+++ b/QT/scan-line/mywindow.cpp
@@ -241,7 +241,7 @@ void MyWindow::DrawLine(int x1, int y1, int x2, int y2, QImage *img){
 
     QColor color(255, 255, 255, 255);
 
-    if(abs(a) < 0.5f){
+    if(abs(a) < 1.0f){
         for(int x = x1; x <= x2; x++){
             int x_form = x - x1;
             int y = a * x_form + y1;