diff --git a/src/geometrygrid.cc b/src/geometrygrid.cc
index 0bb10c705be587b76fd668f6304e439eedc360e2..8b56ffd7e49b9f02677c9f514624ce623e147e48 100644
--- a/src/geometrygrid.cc
+++ b/src/geometrygrid.cc
@@ -65,7 +65,7 @@ int main (int argc, char** argv)
 
   using HostGrid = YaspGrid<2>;
   FieldVector<double,2> bbox = {2.0*M_PI, 2.0*M_PI};
-  std::array num = {4, 12};
+  std::array<int,2> num = {4, 12};
   HostGrid hostGrid{bbox, num}; //, std::bitset<2>{"11"}};
 
   // grid build up of mapped coordinates