diff --git a/unittests/CMakeLists.txt b/unittests/CMakeLists.txt
index eaecc9c..76b76f2 100644
--- a/unittests/CMakeLists.txt
+++ b/unittests/CMakeLists.txt
@@ -43,6 +43,7 @@
   ADT/DeltaAlgorithmTest.cpp
   ADT/DenseMapTest.cpp
   ADT/DenseSetTest.cpp
+  ADT/FoldingSet.cpp
   ADT/ilistTest.cpp
   ADT/ImmutableSetTest.cpp
   ADT/IntervalMapTest.cpp