diff --git a/Solver/CMakeLists.txt b/Solver/CMakeLists.txt
index e01611e5744f217e9b0abad970c09784b549695b..68984e899e797c6c0f4bd917828d9dee7ce1e145 100644
--- a/Solver/CMakeLists.txt
+++ b/Solver/CMakeLists.txt
@@ -18,6 +18,7 @@ functionSpace.cpp
   filters.cpp
   sparsityPattern.cpp
   STensor43.cpp
+  STensor33.cpp
 terms.cpp
 )