diff --git a/mock-certify-plugin/src/main/java/io/mosip/certify/mock/integration/mocks/MdocGenerator.java b/mock-certify-plugin/src/main/java/io/mosip/certify/mock/integration/mocks/MdocGenerator.java
index 2501290..3e28593 100644
--- a/mock-certify-plugin/src/main/java/io/mosip/certify/mock/integration/mocks/MdocGenerator.java
+++ b/mock-certify-plugin/src/main/java/io/mosip/certify/mock/integration/mocks/MdocGenerator.java
@@ -68,7 +68,7 @@ public String generate(Map<String, Object> data, String holderId, String issuerK
         drivingPrivileges.put("issue_date", formattedIssueDate);
         drivingPrivileges.put("expiry_date", formattedExpiryDate);
 
-        data.keySet().forEach(key -> nameSpacedDataBuilder.putEntryString(NAMESPACE, key, data.get(key).toString()));
+        data.keySet().forEach(key -> nameSpacedDataBuilder.putEntryString(NAMESPACE, key, Objects.toString(data.get(key),"")));
 
         NameSpacedData nameSpacedData = nameSpacedDataBuilder.build();
         Map<String, List<byte[]>> generatedIssuerNameSpaces = MdocUtil.generateIssuerNameSpaces(nameSpacedData, new Random(SEED), 16);