diff --git a/src/chat/ChatScreen.js b/src/chat/ChatScreen.js
index 7c64e88..10dea84 100644
--- a/src/chat/ChatScreen.js
+++ b/src/chat/ChatScreen.js
@@ -200,7 +200,7 @@ export default function ChatScreen(props: Props): Node {
           () => undefined,
         );
 
-        if ((content !== undefined && content !== '') || (topic !== undefined && topic !== '')) {
+        if (content !== undefined || topic !== undefined) {
           api.updateMessage(auth, editMessage.id, { content, subject: topic }).catch(error => {
             showErrorAlert(_('Failed to edit message'), error.message);
           });
@@ -287,4 +287,4 @@ export default function ChatScreen(props: Props): Node {
       )}
     </KeyboardAvoider>
   );
-}
+}
\ No newline at end of file
diff --git a/src/compose/ComposeBox.js b/src/compose/ComposeBox.js
index a3e6d83..007d944 100644
--- a/src/compose/ComposeBox.js
+++ b/src/compose/ComposeBox.js
@@ -306,7 +306,7 @@ const ComposeBox: React$AbstractComponent<Props, ImperativeHandle> = forwardRef(
     (videoChatProvider: VideoChatProvider) => {
       if (videoChatProvider.name === 'jitsi_meet') {
         // This is meant to align with the way the webapp generates jitsi video
-        // call IDs. That logic can be found in the ".video_link" click handler
+        // call IDs. That logic can be found in the "video_link" click handler
         // in static/js/compose.js.
         const videoCallId = randomInt(100000000000000, 999999999999999);
         const videoCallUrl = `${videoChatProvider.jitsiServerUrl}/${videoCallId}`;
@@ -554,7 +554,7 @@ const ComposeBox: React$AbstractComponent<Props, ImperativeHandle> = forwardRef(
       result.push('mandatory-topic-empty');
     }
 
-    if (messageInputValue.trim().length === 0) {
+    if (!isEditing && messageInputValue.trim().length === 0) {
       result.push('message-empty');
     }
 
@@ -573,6 +573,7 @@ const ComposeBox: React$AbstractComponent<Props, ImperativeHandle> = forwardRef(
     numUploading,
     anyQuoteAndReplyInProgress,
     messageInputState,
+    isEditing,
   ]);
 
   const submitButtonDisabled = validationErrors.length > 0;
@@ -818,4 +819,4 @@ const ComposeBox: React$AbstractComponent<Props, ImperativeHandle> = forwardRef(
   );
 });
 
-export default ComposeBox;
+export default ComposeBox;
\ No newline at end of file