diff --git a/public/biopet-framework/src/main/scala/nl/lumc/sasc/biopet/tools/Seqstat.scala b/public/biopet-framework/src/main/scala/nl/lumc/sasc/biopet/tools/Seqstat.scala
index 353cbaab79b922658199a7ceb2dd86ca56da91fa..822487bf9f79c45bd913ef247984b6c6d1a42f3f 100644
--- a/public/biopet-framework/src/main/scala/nl/lumc/sasc/biopet/tools/Seqstat.scala
+++ b/public/biopet-framework/src/main/scala/nl/lumc/sasc/biopet/tools/Seqstat.scala
@@ -194,6 +194,9 @@ object Seqstat extends ToolCommand {
     val readQual = record.getBaseQualityString
     val readNucleotides = record.getReadString
 
+    if (record.length >= readStats.lengths.size) // Extends array when length not yet possible
+      (0 to (record.length - readStats.lengths.size)).foreach(_ => readStats.lengths.append(0))
+
     readStats.lengths(record.length) += 1
 
     for (t <- 0 until record.length()) {