diff --git a/src/wp-includes/l10n/class-wp-translation-file-mo.php b/src/wp-includes/l10n/class-wp-translation-file-mo.php
index 3f5e72597ca5f..f50c0ec1cf2d1 100644
--- a/src/wp-includes/l10n/class-wp-translation-file-mo.php
+++ b/src/wp-includes/l10n/class-wp-translation-file-mo.php
@@ -154,7 +154,7 @@ protected function parse_file(): bool {
 			// Metadata about the MO file is stored in the first translation entry.
 			if ( '' === $original ) {
 				foreach ( explode( "\n", $translation ) as $meta_line ) {
-					if ( '' === $meta_line ) {
+					if ( '' === $meta_line || ! str_contains( $meta_line, ':' ) ) {
 						continue;
 					}