diff --git a/src/main/java/gov/usgs/earthquake/nshmp/HazardCalc.java b/src/main/java/gov/usgs/earthquake/nshmp/HazardCalc.java
index 9df0cfb08cd7dbade5c0fce18f4a289f66749d7c..4040521bef2279741808d36e231c73055b212d7e 100644
--- a/src/main/java/gov/usgs/earthquake/nshmp/HazardCalc.java
+++ b/src/main/java/gov/usgs/earthquake/nshmp/HazardCalc.java
@@ -129,7 +129,7 @@ public class HazardCalc {
           log.info("Sites: " + Sites.toString(sites));
           out = calc(model, config, sites, OptionalDouble.of(vs30), log);
         }
-        out = out.getParent();
+        out = checkNotNull(out.getParent());
 
       }