diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/overlord/ForkingTaskRunner.java b/indexing-service/src/main/java/org/apache/druid/indexing/overlord/ForkingTaskRunner.java
index 83451c490a80..c39df49a79d8 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/overlord/ForkingTaskRunner.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/overlord/ForkingTaskRunner.java
@@ -24,6 +24,7 @@
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Joiner;
 import com.google.common.base.Optional;
+import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
@@ -316,7 +317,7 @@ public TaskStatus call()
                             if (propName.startsWith(CHILD_PROPERTY_PREFIX)) {
                               command.addSystemProperty(
                                   propName.substring(CHILD_PROPERTY_PREFIX.length()),
-                                  task.getContextValue(propName)
+                                  Preconditions.checkNotNull(task.getContextValue(propName), propName).toString()
                               );
                             }
                           }