diff --git a/input.cc b/input.cc
index fee71c357..9d15b5be0 100644
--- a/input.cc
+++ b/input.cc
@@ -815,7 +815,7 @@ void read_atomicdata_files() {
       // store the ions data to memory and set up the ions zeta and levellist
 
       globals::elements[element].ions[ion] = {
-          .levels = static_cast<EnergyLevel *>(malloc(nlevelsmax * sizeof(EnergyLevel))),
+          .levels = static_cast<EnergyLevel *>(calloc(nlevelsmax, sizeof(EnergyLevel))),
           .ionstage = ionstage,
           .nlevels = nlevelsmax,
           .nlevels_nlte = 0,