diff --git a/lib/jazzy/sourcekitten.rb b/lib/jazzy/sourcekitten.rb
index 880e3f1fc..c056ba82c 100644
--- a/lib/jazzy/sourcekitten.rb
+++ b/lib/jazzy/sourcekitten.rb
@@ -591,9 +591,11 @@ def self.make_source_declarations(docs, parent = nil, mark = SourceMark.new)
         inherited_types = doc['key.inheritedtypes'] || []
         declaration.inherited_types =
           inherited_types.map { |type| type['key.name'] }.compact
-        if xml_declaration = doc['key.fully_annotated_decl']
-          declaration.async = swift_async?(xml_declaration)
-        end
+        declaration.async =
+          doc['key.async'] ||
+          if xml_declaration = doc['key.fully_annotated_decl']
+            swift_async?(xml_declaration)
+          end
 
         next unless make_doc_info(doc, declaration)
         declaration.children = make_substructure(doc, declaration)
diff --git a/lib/jazzy/symbol_graph/sym_node.rb b/lib/jazzy/symbol_graph/sym_node.rb
index 31f799018..770e7673b 100644
--- a/lib/jazzy/symbol_graph/sym_node.rb
+++ b/lib/jazzy/symbol_graph/sym_node.rb
@@ -23,6 +23,7 @@ def children_to_sourcekit
 
     # A SymNode is a node of the reconstructed syntax tree holding a symbol.
     # It can turn itself into SourceKit and helps decode extensions.
+    # rubocop:disable Metrics/ClassLength
     class SymNode < BaseNode
       attr_accessor :symbol
       attr_writer :override
@@ -111,6 +112,11 @@ def inherits_clause
         " : #{superclass_name}"
       end
 
+      # approximately...
+      def async?
+        symbol.declaration =~ /async[^\)]*$/
+      end
+
       def full_declaration
         symbol.availability
               .append(symbol.declaration + inherits_clause + where_clause)
@@ -129,6 +135,7 @@ def to_sourcekit
           'key.accessibility' => symbol.acl,
           'key.parsed_decl' => declaration,
           'key.annotated_decl' => xml_declaration,
+          'key.async' => async?,
         }
         if docs = symbol.doc_comments
           hash['key.doc.comment'] = docs
@@ -158,5 +165,6 @@ def <=>(other)
         symbol <=> other.symbol
       end
     end
+    # rubocop:enable Metrics/ClassLength
   end
 end