diff --git a/biopet/seqstat.wdl b/biopet/seqstat.wdl
index 959d9efd3d84ae9f84908ff1bdfb83c6c140f45f..c1e83a2f86919ad181dfaa4498c0d94b96752e15 100644
--- a/biopet/seqstat.wdl
+++ b/biopet/seqstat.wdl
@@ -9,9 +9,9 @@ task Generate {
         File fastqR1
         File? fastqR2
         String outputFile
-        String sample = "sample"
-        String library = "library"
-        String readgroup = "readgroup"
+        String sample
+        String library
+        String readgroup
 
         Int memory = 4
         Float memoryMultiplier = 2.0