diff --git a/waku-messages/message-variables/waku-message-variables.dmn b/waku-messages/message-variables/waku-message-variables.dmn
index dd0cca3f..236476a0 100644
--- a/waku-messages/message-variables/waku-message-variables.dmn
+++ b/waku-messages/message-variables/waku-message-variables.dmn
@@ -29,7 +29,7 @@
           <text>"waku_payment_pending_ismatch"</text>
         </inputEntry>
         <outputEntry id="LiteralExpression_08whd59">
-          <text>"\nInvoice no: " + invoice.invoiceId + "\nAmount: " + invoice.invoiceAmount_str + "\nDate submitted: " + invoice.invoiceDate + "\nStatus: " + invoice.invoiceStatus + "\nFinance Comments: " + invoice.commentsFinance</text>
+          <text>"\nInvoice no: " + str(invoice.invoiceId) + "\nAmount: " + invoice.invoiceAmount_str + "\nDate submitted: " + invoice.invoiceDate + "\nStatus: " + invoice.invoiceStatus + "\nFinance Comments: " + invoice.commentsFinance</text>
         </outputEntry>
       </rule>
       <rule id="DecisionRule_0ox5iuo">
@@ -43,7 +43,7 @@
           <text>"waku_payment_pending_not_ismatch"</text>
         </inputEntry>
         <outputEntry id="LiteralExpression_1f972mh">
-          <text>"\nInvoice no: " + invoice.invoiceId + "\nAmount: " + invoice.invoiceAmount_str + "\nDate submitted: " + invoice.invoiceDate + "\nStatus: " + invoice.invoiceStatus + "\nProject Lead Comments: " + invoice.commentsProjectLead + "\nFinance Comments: " + invoice.commentsFinance</text>
+          <text>"\nInvoice no: " + str(invoice.invoiceId) + "\nAmount: " + invoice.invoiceAmount_str + "\nDate submitted: " + invoice.invoiceDate + "\nStatus: " + invoice.invoiceStatus + "\nProject Lead Comments: " + invoice.commentsProjectLead + "\nFinance Comments: " + invoice.commentsFinance</text>
         </outputEntry>
       </rule>
       <rule id="DecisionRule_0a36qh6">
@@ -57,7 +57,7 @@
           <text>"waku_invoice_rejected-Team_Lead"</text>
         </inputEntry>
         <outputEntry id="LiteralExpression_1sx6jui">
-          <text>"\nInvoice no: " + invoice.invoiceId + "\nAmount: " + invoice.invoiceAmount_str + "\nDate submitted: " + invoice.invoiceDate + "\nStatus: " + invoice.invoiceStatus + "\nFinance Comments: " + invoice.commentsFinance</text>
+          <text>"\nInvoice no: " + str(invoice.invoiceId) + "\nAmount: " + invoice.invoiceAmount_str + "\nDate submitted: " + invoice.invoiceDate + "\nStatus: " + invoice.invoiceStatus + "\nFinance Comments: " + invoice.commentsFinance</text>
         </outputEntry>
       </rule>
       <rule id="DecisionRule_1ejqucj">
@@ -71,7 +71,7 @@
           <text>"waku_invoice_rejected-Finance"</text>
         </inputEntry>
         <outputEntry id="LiteralExpression_0ap9kmf">
-          <text>"\nInvoice no: " + invoice.invoiceId + "\nAmount: " + invoice.invoiceAmount_str + "\nDate submitted: " + invoice.invoiceDate + "\nStatus: " + invoice.invoiceStatus + "\nProject Lead Comments: " + invoice.commentsProjectLead</text>
+          <text>"\nInvoice no: " + str(invoice.invoiceId) + "\nAmount: " + invoice.invoiceAmount_str + "\nDate submitted: " + invoice.invoiceDate + "\nStatus: " + invoice.invoiceStatus + "\nProject Lead Comments: " + invoice.commentsProjectLead</text>
         </outputEntry>
       </rule>
       <rule id="DecisionRule_03x15pb">
@@ -85,7 +85,7 @@
           <text></text>
         </inputEntry>
         <outputEntry id="LiteralExpression_1x5klct">
-          <text>"\nInvoice no: " + invoice.invoiceId + "\nAmount: " + invoice.invoiceAmount_str + "\nDate submitted: " + invoice.invoiceDate  + "\nStatus: " + invoice.invoiceStatus</text>
+          <text>"\nInvoice no: " + str(invoice.invoiceId) + "\nAmount: " + invoice.invoiceAmount_str + "\nDate submitted: " + invoice.invoiceDate  + "\nStatus: " + invoice.invoiceStatus</text>
         </outputEntry>
       </rule>
     </decisionTable>