diff --git a/main/src/com/google/refine/model/Row.java b/main/src/com/google/refine/model/Row.java
index 1188c24f8..3ecc4a244 100644
--- a/main/src/com/google/refine/model/Row.java
+++ b/main/src/com/google/refine/model/Row.java
@@ -239,7 +239,7 @@ public class Row implements HasFields, Jsonizable {
     public String toString() {
         StringBuffer result = new StringBuffer();
         for (Cell cell : cells) {
-            result.append(cell.toString());
+            result.append(cell == null ? "null" : cell.toString());
             result.append(",");
         }
         return result.toString();