diff --git a/src/main/java/net/kemitix/wiser/assertions/WiserAssertions.java b/src/main/java/net/kemitix/wiser/assertions/WiserAssertions.java
index 50dbf4c..c19eb40 100644
--- a/src/main/java/net/kemitix/wiser/assertions/WiserAssertions.java
+++ b/src/main/java/net/kemitix/wiser/assertions/WiserAssertions.java
@@ -184,7 +184,7 @@ public final class WiserAssertions {
             throws IOException, MessagingException {
         Object content = getMimeMessage(message).getContent();
         if (content instanceof MimeMessage) {
-            return (String) content;
+            return content.toString();
         }
         if (content instanceof MimeMultipart) {
             return getMimeMultipartAsString((MimeMultipart) content);