diff --git a/mandelbrot.c b/mandelbrot.c
index e473255bd33c2cdf63173d0ec84b7d2a691bfb59..46e206167d68e8185cb55488e81eea7f36352771 100644
--- a/mandelbrot.c
+++ b/mandelbrot.c
@@ -16,8 +16,8 @@ int main()
 {
          /* screen ( integer) coordinate */
        int iX,iY;
-       const int iXmax = 2000;
-       const int iYmax = 2000;
+       const int iXmax = 4000;
+       const int iYmax = 4000;
        /* world ( double) coordinate = parameter plane*/
        double Cx,Cy;
        const double CxMin=-2.5;