diff --git a/preprocessor/IncidenceMatrix.cc b/preprocessor/IncidenceMatrix.cc
index 286eb1a26..3839a1ccc 100644
--- a/preprocessor/IncidenceMatrix.cc
+++ b/preprocessor/IncidenceMatrix.cc
@@ -17,6 +17,8 @@
  * along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <cstdlib>
+#include <cstring>
 
 #include "IncidenceMatrix.hh"
 
diff --git a/preprocessor/Makefile b/preprocessor/Makefile
index 1712c2ac9..204754aa8 100644
--- a/preprocessor/Makefile
+++ b/preprocessor/Makefile
@@ -29,7 +29,7 @@ OBJS = \
 	ExprNode.o \
 	ModelNormalization.o \
 	ModelBlocks.o \
-    IncidenceMatrix.o \
+	IncidenceMatrix.o \
 	BlockTriangular.o \
 	Model_Graph.o \
 	SymbolGaussElim.o \