diff --git a/inst/dist_obj/PiecewiseLinearDistribution.m b/inst/dist_obj/PiecewiseLinearDistribution.m
index 052630f7..0e100135 100644
--- a/inst/dist_obj/PiecewiseLinearDistribution.m
+++ b/inst/dist_obj/PiecewiseLinearDistribution.m
@@ -244,7 +244,7 @@ function disp (this)
         Fa_b = plcdf ([lx, ux], this.x, this.Fx);
         m = plinv (sum (Fa_b) / 2, this.x, this.Fx);
       else
-        m = plstat (this.x, this.Fx);
+        m = plinv (0.5, this.x, this.Fx);
       endif
     endfunction
 
diff --git a/inst/dist_obj/PoissonDistribution.m b/inst/dist_obj/PoissonDistribution.m
index 3d7bea07..4b27d241 100644
--- a/inst/dist_obj/PoissonDistribution.m
+++ b/inst/dist_obj/PoissonDistribution.m
@@ -266,7 +266,7 @@ function disp (this)
         Fa_b = poisscdf ([lx, ux], this.lambda);
         m = poissinv (sum (Fa_b) / 2, this.lambda);
       else
-        m = this.lambda .* sqrt (2 * log (2));
+        m = poissinv (0.5, this.lambda);
       endif
     endfunction