diff --git a/exercises/solution/exercise-properties/problem.hh b/exercises/solution/exercise-properties/problem.hh
index f218701a74272c6e51cbf6dd6cca45f1313787f5..b1c107aeab974f5e0c8b967a55795662aa1b3386 100644
--- a/exercises/solution/exercise-properties/problem.hh
+++ b/exercises/solution/exercise-properties/problem.hh
@@ -23,6 +23,7 @@
 #ifndef DUMUX_INCOMPRESSIBLE_TWOP_TEST_PROBLEM_HH
 #define DUMUX_INCOMPRESSIBLE_TWOP_TEST_PROBLEM_HH
 
+#include <dumux/material/components/trichloroethene.hh>
 #include <dumux/porousmediumflow/problem.hh>
 #include <dumux/common/properties.hh>