diff --git a/applications/lazstats/source/forms/analysis/descriptive/plotxyunit.pas b/applications/lazstats/source/forms/analysis/descriptive/plotxyunit.pas
index c5f786a8c..03f472edd 100644
--- a/applications/lazstats/source/forms/analysis/descriptive/plotxyunit.pas
+++ b/applications/lazstats/source/forms/analysis/descriptive/plotxyunit.pas
@@ -234,6 +234,12 @@ begin
     exit;
   end;
 
+  // Trim array lengths
+  SetLength(Xpoints, NoCases);
+  SetLength(Ypoints, NoCases);
+  SetLength(UpConf, NoCases);
+  SetLength(lowConf, NoCases);
+
   // sort on X
   SortOnX(XPoints, YPoints);