diff --git a/util/update_copyrights b/util/update_copyrights
index 89300539d4..8f8e96c048 100644
--- a/util/update_copyrights
+++ b/util/update_copyrights
@@ -322,7 +322,7 @@ foreach $file (keys %file_types) {
 				close(SOURCE) if (eof(SOURCE));
 				next;
 			}
-			if (/^<!DOCTYPE/) {
+			if (/^<!DOCTYPE.*\[$/) {
 				while (!eof(SOURCE)) {
 					$_ = <SOURCE>;
 					next if (eof(SOURCE));