diff --git a/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/GtfToGenePred.scala b/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/GtfToGenePred.scala
index aa5b07742d744b2b2619d1f07d9df80b6a5d74c3..631c76fe0e7da95515379e862f823363b529ec0e 100644
--- a/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/GtfToGenePred.scala
+++ b/biopet-extensions/src/main/scala/nl/lumc/sasc/biopet/extensions/GtfToGenePred.scala
@@ -35,5 +35,6 @@ class GtfToGenePred(val root: Configurable) extends BiopetCommandLineFunction {
     conditional(impliedStopAfterCds, "-impliedStopAfterCds") +
     conditional(simple, "-simple") +
     conditional(geneNameAsName2, "-geneNameAsName2") +
+    repeat(inputGtfs) +
     (if (outputAsStsout) "" else " > " + required(outputGenePred))
 }