1 files changed, 2 insertions, 2 deletions

diff --git a/src/main/scala/uk/ac/ox/cs/acqua/util/AcquaConfig.scala b/src/main/scala/uk/ac/ox/cs/acqua/util/AcquaConfig.scala
index 990afb2..ec550c2 100644
--- a/src/main/scala/uk/ac/ox/cs/acqua/util/AcquaConfig.scala
+++ b/src/main/scala/uk/ac/ox/cs/acqua/util/AcquaConfig.scala
@@ -192,12 +192,12 @@ object AcquaConfig {
       case 'data => {
         val paths = v.get[List[os.Path]]
         val ellipsis = if (paths.length > 1) " [...]" else "" 
-        Logger print s"Data files: ${paths.head}$ellipsis"
+        Logger print s"Data files: ${paths.headOption.getOrElse("NONE")}$ellipsis"
       }
       case 'queries => {
         val paths = v.get[List[os.Path]]
         val ellipsis = if (paths.length > 1) " [...]" else "" 
-        Logger print s"Query files: ${paths.head}$ellipsis"
+        Logger print s"Query files: ${paths.headOption.getOrElse("NONE")}$ellipsis"
       }
       case 'answers => Logger print s"Path to answers: ${v.get[os.Path]}"
       case 'transitive => Logger print s"Include property chain axioms: ${v.get[Boolean]}"