diff --git a/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/json/MetadataDocumentJsonSerializer.java b/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/json/MetadataDocumentJsonSerializer.java
index f3565403a..30efdf92a 100644
--- a/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/json/MetadataDocumentJsonSerializer.java
+++ b/lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/json/MetadataDocumentJsonSerializer.java
@@ -851,7 +851,9 @@ public class MetadataDocumentJsonSerializer {
   
   private void appendDynamicExpression(JsonGenerator json, 
       EdmDynamicExpression dynExp, String termName) throws SerializerException, IOException {
-    json.writeFieldName(termName);
+    if (termName != null) {
+	  json.writeFieldName(termName);
+    }
     switch (dynExp.getExpressionType()) {
     // Logical
     case And: