diff --git a/lib/asciidoctor/parser.rb b/lib/asciidoctor/parser.rb
index c6f5b1e99..400e154fd 100644
--- a/lib/asciidoctor/parser.rb
+++ b/lib/asciidoctor/parser.rb
@@ -818,7 +818,7 @@ def self.next_block(reader, parent, attributes = {}, options = {})
     unless block
       case block_context
       when :listing, :source
-        if block_context == :source || (language = attributes[1] ? nil : language = attributes[2] || doc_attrs['source-language'])
+        if block_context == :source || (language = attributes[1] ? nil : attributes[2] || doc_attrs['source-language'])
           if language
             attributes['style'] = 'source'
             attributes['language'] = language