diff --git a/src/wp-includes/shortcodes.php b/src/wp-includes/shortcodes.php
index 2d19e21..3da5b67 100644
--- a/src/wp-includes/shortcodes.php
+++ b/src/wp-includes/shortcodes.php
@@ -305,7 +305,11 @@
 function strip_shortcode_tag( $m ) {
 	// allow [[foo]] syntax for escaping a tag
 	if ( $m[1] == '[' && $m[6] == ']' ) {
-		return '[' . substr( $m[0], 2, -1 );
+		// return escaped opening bracket to prevent expansion during get_the_excerpt
+		return '[' . substr( $m[0], 2, -1 );
 	}
 	return $m[1] . $m[6];
 }