diff --git a/cli-lanterna/src/main/groovy/com/muwire/clilanterna/AddCommentView.groovy b/cli-lanterna/src/main/groovy/com/muwire/clilanterna/AddCommentView.groovy
index 4b0e60fe..4c60de83 100644
--- a/cli-lanterna/src/main/groovy/com/muwire/clilanterna/AddCommentView.groovy
+++ b/cli-lanterna/src/main/groovy/com/muwire/clilanterna/AddCommentView.groovy
@@ -3,6 +3,8 @@ package com.muwire.clilanterna
 import com.googlecode.lanterna.gui2.TextBox
 import com.googlecode.lanterna.gui2.TextGUI
 import com.googlecode.lanterna.gui2.Window
+import com.googlecode.lanterna.gui2.dialogs.MessageDialog
+import com.googlecode.lanterna.gui2.dialogs.MessageDialogButton
 import com.googlecode.lanterna.TerminalSize
 import com.googlecode.lanterna.gui2.BasicWindow
 import com.googlecode.lanterna.gui2.Button
@@ -10,6 +12,7 @@ import com.googlecode.lanterna.gui2.GridLayout
 import com.googlecode.lanterna.gui2.GridLayout.Alignment
 import com.googlecode.lanterna.gui2.LayoutData
 import com.googlecode.lanterna.gui2.Panel
+import com.muwire.core.Constants
 import com.muwire.core.Core
 import com.muwire.core.SharedFile
 import com.muwire.core.files.UICommentEvent
@@ -49,11 +52,16 @@ class AddCommentView extends BasicWindow {
         
         Button saveButton = new Button("Save", {
             String newComment = textBox.getText()
-            newComment = Base64.encode(DataUtil.encodei18nString(newComment))
-            String encodedOldComment = sharedFile.getComment()
-            sharedFile.setComment(newComment)
-            core.eventBus.publish(new UICommentEvent(sharedFile : sharedFile, oldComment : encodedOldComment))
-            close()
+            if (newComment.length() > Constants.MAX_COMMENT_LENGTH) {
+                String error = "Your comment is too long - ${newComment.length()} bytes.  Maximum is $Constants.MAX_COMMENT_LENGTH bytes"
+                MessageDialog.showMessageDialog(textGUI, "Comment Too Long", error, MessageDialogButton.Close)
+            } else {
+                newComment = Base64.encode(DataUtil.encodei18nString(newComment))
+                String encodedOldComment = sharedFile.getComment()
+                sharedFile.setComment(newComment)
+                core.eventBus.publish(new UICommentEvent(sharedFile : sharedFile, oldComment : encodedOldComment))
+                close()
+            }
         })
         Button cancelButton = new Button("Cancel", {close()})