diff --git a/haas-spim-benchmark/src/main/java/cz/it4i/fiji/haas_spim_benchmark/core/SPIMComputationAccessorDecoratorWithTimeout.java b/haas-spim-benchmark/src/main/java/cz/it4i/fiji/haas_spim_benchmark/core/SPIMComputationAccessorDecoratorWithTimeout.java
index 8f215c3ac7f5aa673c93fca22754cc005d00e724..388b350ac5034a0202ae585bd1aeb15deb185728 100644
--- a/haas-spim-benchmark/src/main/java/cz/it4i/fiji/haas_spim_benchmark/core/SPIMComputationAccessorDecoratorWithTimeout.java
+++ b/haas-spim-benchmark/src/main/java/cz/it4i/fiji/haas_spim_benchmark/core/SPIMComputationAccessorDecoratorWithTimeout.java
@@ -23,7 +23,7 @@ public class SPIMComputationAccessorDecoratorWithTimeout implements SPIMComputat
 				set.clear();
 			}
 			set.addAll(decorated.getChangedFiles());
-			return null;
+			return set;
 		});
 	}