diff --git a/src/averageinterface.hh b/src/averageinterface.hh
index e78406ec4b89b62e2ac3b1bb92824d747ec6621a..2544214913b42fca5bc8e030e7df65c014bc2f2b 100644
--- a/src/averageinterface.hh
+++ b/src/averageinterface.hh
@@ -9,6 +9,13 @@
 #include <dune/ag-common/surfmassmatrix.hh>
 #include "svd.hh"
 
+#ifdef HAVE_IPOPT
+#include "coin/IpTNLP.hpp"
+#include "coin/IpIpoptApplication.hpp"
+#else
+#error You need IPOpt for this header!
+#endif
+
 template <class GridType>
 class PressureAverager : public Ipopt::TNLP
 {