diff --git a/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BoxAggregator.java b/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BoxAggregator.java
index 7f7aede..d4449e4 100644
--- a/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BoxAggregator.java
+++ b/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BoxAggregator.java
@@ -52,15 +52,17 @@ public class BoxAggregator implements CustomAggregator {
 
         buckets.forEachOrdered((final long bucketId, final PercentilesAggregator percentilesAggregator) -> {
             final Percentiles percentiles = percentilesAggregator.getPercentiles();
-            csv.append(String.format(Locale.US, "%d,%d,%d,%d,%d,%d", //
-                    bucketId / 1000, //
-                    percentiles.get("0.000"), //
-                    percentiles.get("25.000"), //
-                    percentiles.get("50.000"), //
-                    percentiles.get("75.000"), //
-                    percentiles.get("100.000")//
-            ));
-            csv.append("\n");
+            if (percentiles.get("25.000") != null) {
+                csv.append(String.format(Locale.US, "%d,%d,%d,%d,%d,%d", //
+                        bucketId / 1000, //
+                        percentiles.get("0.000"), //
+                        percentiles.get("25.000"), //
+                        percentiles.get("50.000"), //
+                        percentiles.get("75.000"), //
+                        percentiles.get("100.000")//
+                ));
+                csv.append("\n");
+            }
         });
 
         return csv.toString();