diff --git a/src/main/java/net/kemitix/wiser/assertions/MimeMessageException.java b/src/main/java/net/kemitix/wiser/assertions/MimeMessageException.java
new file mode 100644
index 0000000..e407812
--- /dev/null
+++ b/src/main/java/net/kemitix/wiser/assertions/MimeMessageException.java
@@ -0,0 +1,39 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Paul Campbell
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies
+ * or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
+ * AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package net.kemitix.wiser.assertions;
+
+/**
+ * Assertions caused by errors while parsing mime message content.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class MimeMessageException extends RuntimeException {
+
+    /**
+     * Create an assertion with a message.
+     *
+     * @param message the message
+     */
+    public MimeMessageException(final String message) {
+        super(message);
+    }
+}
diff --git a/src/main/java/net/kemitix/wiser/assertions/WiserAssertionException.java b/src/main/java/net/kemitix/wiser/assertions/WiserAssertionException.java
new file mode 100644
index 0000000..59053e6
--- /dev/null
+++ b/src/main/java/net/kemitix/wiser/assertions/WiserAssertionException.java
@@ -0,0 +1,40 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Paul Campbell
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies
+ * or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
+ * AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package net.kemitix.wiser.assertions;
+
+/**
+ * Assertions caused by {@link WiserAssertions}.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public class WiserAssertionException extends RuntimeException {
+
+    /**
+     * Create a wrapper for the cause.
+     *
+     * @param cause the original exception
+     */
+    public WiserAssertionException(final Throwable cause) {
+        super(cause);
+    }
+
+}
diff --git a/src/main/java/net/kemitix/wiser/assertions/WiserAssertions.java b/src/main/java/net/kemitix/wiser/assertions/WiserAssertions.java
index 1d3b26a..e8aa8d1 100644
--- a/src/main/java/net/kemitix/wiser/assertions/WiserAssertions.java
+++ b/src/main/java/net/kemitix/wiser/assertions/WiserAssertions.java
@@ -187,12 +187,12 @@ public final class WiserAssertions {
      *
      * @return the product of the supplier
      */
-    @SuppressWarnings("illegalCatch")
+    @SuppressWarnings("illegalcatch")
     public static <T> T unchecked(final ThrowingSupplier<T> supplier) {
         try {
             return supplier.get();
         } catch (Throwable e) {
-            throw new RuntimeException(e);
+            throw new WiserAssertionException(e);
         }
     }
 
@@ -275,7 +275,7 @@ public final class WiserAssertions {
     @SuppressWarnings("npathcomplexity")
     private String getMimeMessageBody(final WiserMessage message)
             throws IOException, MessagingException {
-        Object content = getMimeMessage(message).getContent();
+        final Object content = getMimeMessage(message).getContent();
         String result = null;
         if (content instanceof String) {
             result = (String) content;
@@ -287,7 +287,7 @@ public final class WiserAssertions {
             result = getMimeMultipartAsString((MimeMultipart) content);
         }
         if (result == null) {
-            throw new RuntimeException("Unexpected MimeMessage content");
+            throw new MimeMessageException("Unexpected MimeMessage content");
         }
         return result;
     }