diff --git a/src/backend/filters/spatialAnalysis.cpp b/src/backend/filters/spatialAnalysis.cpp
index 2453cbe..91faebf 100644
--- a/src/backend/filters/spatialAnalysis.cpp
+++ b/src/backend/filters/spatialAnalysis.cpp
@@ -15,6 +15,10 @@
  *	You should have received a copy of the GNU General Public License
  *	along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
+
+//GSL_spmatrix seems to be missing size_t definition
+#include <cstddef>
+
 #include <gsl/gsl_sf_gamma.h>
 #include <gsl/gsl_spmatrix.h>
 
