diff --git a/dune/solvers/iterationsteps/blockgssteps.hh b/dune/solvers/iterationsteps/blockgssteps.hh
index 00b7e8eede4397e4efddd25fb9d555b79214bae7..7c7cec4084f725182f290ad0ea50fe3cf21fbdc9 100644
--- a/dune/solvers/iterationsteps/blockgssteps.hh
+++ b/dune/solvers/iterationsteps/blockgssteps.hh
@@ -1,6 +1,7 @@
 #ifndef DUNE_SOLVERS_ITERATIONSTEPS_BLOCKGSSTEPS_HH
 #define DUNE_SOLVERS_ITERATIONSTEPS_BLOCKGSSTEPS_HH
 
+#include <cassert>
 #include <functional>
 
 #include <dune/common/parametertree.hh>