diff --git a/includes/CommentParser.php b/includes/CommentParser.php
index 250beca6d..e563a2bac 100644
--- a/includes/CommentParser.php
+++ b/includes/CommentParser.php
@@ -600,7 +600,8 @@ class CommentParser {
 				}
 
 				if ( $event === 'leave' && $node !== $timestampNode ) {
-					$length += $node instanceof Text ? mb_strlen( $node->textContent ?? '' ) : 0;
+					$length += $node instanceof Text ?
+						mb_strlen( CommentUtils::htmlTrim( $node->textContent ?? '' ) ) : 0;
 				}
 
 				// Find the closest link before timestamp that links to the user's user page.
diff --git a/modules/Parser.js b/modules/Parser.js
index 2929598c4..c34325a88 100644
--- a/modules/Parser.js
+++ b/modules/Parser.js
@@ -587,7 +587,8 @@ Parser.prototype.findSignature = function ( timestampNode, until ) {
 			}
 
 			if ( event === 'leave' && node !== timestampNode ) {
-				length += node.nodeType === Node.TEXT_NODE ? codePointLength( node.textContent ) : 0;
+				length += node.nodeType === Node.TEXT_NODE ?
+					codePointLength( utils.htmlTrim( node.textContent ) ) : 0;
 			}
 
 			// Find the closest link before timestamp that links to the user's user page.