diff --git a/collatex-tools/src/main/java/eu/interedition/collatex/tools/CollationPipe.java b/collatex-tools/src/main/java/eu/interedition/collatex/tools/CollationPipe.java
index <HASH>..<HASH> 100644
--- a/collatex-tools/src/main/java/eu/interedition/collatex/tools/CollationPipe.java
+++ b/collatex-tools/src/main/java/eu/interedition/collatex/tools/CollationPipe.java
@@ -150,9 +150,7 @@ public class CollationPipe {
         }
 
         final VariantGraph variantGraph = new VariantGraph();
-        for (SimpleWitness witness : witnesses) {
-            collationAlgorithm.collate(variantGraph, witness);
-        }
+        collationAlgorithm.collate(variantGraph, witnesses);
 
         if (joined && !commandLine.hasOption("t")) {
             VariantGraph.JOIN.apply(variantGraph);
Bug fix for the "non progressive alignment" exception in the command-line tool of CollateX when using the <I>.X version of the DekkerAlgorithm.