diff --git a/src/core/npt.cpp b/src/core/npt.cpp
index 1a202777d05..ac9b2d42316 100644
--- a/src/core/npt.cpp
+++ b/src/core/npt.cpp
@@ -16,11 +16,13 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-#include "npt.hpp"
+#include <cmath>
+
 #include "communication.hpp"
 #include "config.hpp"
 #include "errorhandling.hpp"
 #include "integrate.hpp"
+#include "npt.hpp"
 
 #ifdef NPT
 void synchronize_npt_state(int n_steps) {
@@ -28,8 +30,13 @@ void synchronize_npt_state(int n_steps) {
   MPI_Bcast(&nptiso.p_inst, 1, MPI_DOUBLE, 0, comm_cart);
   MPI_Bcast(&nptiso.p_diff, 1, MPI_DOUBLE, 0, comm_cart);
   MPI_Bcast(&nptiso.volume, 1, MPI_DOUBLE, 0, comm_cart);
-  if (this_node == 0)
-    nptiso.p_inst_av /= 1.0 * n_steps;
+  if (this_node == 0) {
+    if (n_steps == 0) {
+      nptiso.p_inst_av = std::nan("");
+    } else {
+      nptiso.p_inst_av /= 1.0 * n_steps;
+    }
+  }
   MPI_Bcast(&nptiso.p_inst_av, 1, MPI_DOUBLE, 0, comm_cart);
 }