diff --git a/mandelbrot.c b/mandelbrot.c
index cdab641c22b60c9942373e2148a7ae45e71bbb9e..945d9de4f39911e936d97d1c7e882afcbedf93a6 100644
--- a/mandelbrot.c
+++ b/mandelbrot.c
@@ -16,8 +16,8 @@ int main()
 {
          /* screen ( integer) coordinate */
        int iX,iY;
-       const int iXmax = 1500;
-       const int iYmax = 1500;
+       const int iXmax = 4000;
+       const int iYmax = 4000;
        /* world ( double) coordinate = parameter plane*/
        double Cx,Cy;
        const double CxMin=-2.5;