diff --git a/zanata-model/src/main/java/org/zanata/model/HTextFlowTarget.java b/zanata-model/src/main/java/org/zanata/model/HTextFlowTarget.java
index 3754804b56..ce95bcab76 100644
--- a/zanata-model/src/main/java/org/zanata/model/HTextFlowTarget.java
+++ b/zanata-model/src/main/java/org/zanata/model/HTextFlowTarget.java
@@ -395,9 +395,16 @@ public HTextFlowTargetReviewComment addReviewComment(String comment,
 
     @Override
     public String toString() {
-        return MoreObjects.toStringHelper(this).add("contents", getContents())
-                .add("locale", getLocale()).add("state", getState())
-                .add("comment", getComment())
+        MoreObjects.ToStringHelper helper =
+                MoreObjects.toStringHelper(this)
+                        .add("contents", getContents())
+                        .add("locale", getLocale())
+                        .add("state", getState())
+                        .add("comment", getComment());
+        if (getTextFlow() == null) {
+            return helper.toString();
+        }
+        return helper
                 .add("textFlow", getTextFlow().getContents()).toString();
     }