diff --git a/src/Makefile.am b/src/Makefile.am
index 2f44a780e73d488872c27223c404b6f089ca03c9..abbbc97577b748d637e487fc135b9c79c2e48296 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -79,6 +79,7 @@ AM_CXXFLAGS = \
 	-Wno-unused-variable
 
 AM_CPPFLAGS = \
+	-DDUNE_FMatrix_WITH_CHECKING \
 	$(DUNE_CPPFLAGS) \
 	$(PYTHON_CPPFLAGS) \
 	$(ALUGRID_CPPFLAGS) \