diff --git a/src/wp-includes/class-wp-theme-json-resolver.php b/src/wp-includes/class-wp-theme-json-resolver.php
index 4d5bf3dce9ee3..5e9e2334e4e2a 100644
--- a/src/wp-includes/class-wp-theme-json-resolver.php
+++ b/src/wp-includes/class-wp-theme-json-resolver.php
@@ -106,11 +106,12 @@ protected static function read_json_file( $file_path ) {
 			if ( array_key_exists( $file_path, static::$theme_json_file_cache ) ) {
 				return static::$theme_json_file_cache[ $file_path ];
 			}
-
-			$decoded_file = wp_json_file_decode( $file_path, array( 'associative' => true ) );
-			if ( is_array( $decoded_file ) ) {
-				static::$theme_json_file_cache[ $file_path ] = $decoded_file;
-				return static::$theme_json_file_cache[ $file_path ];
+			if ( is_readable( $file_path ) ) {
+				$decoded_file = wp_json_file_decode( $file_path, array( 'associative' => true ) );
+				if ( is_array( $decoded_file ) ) {
+					static::$theme_json_file_cache[ $file_path ] = $decoded_file;
+					return static::$theme_json_file_cache[ $file_path ];
+				}
 			}
 		}