diff --git a/lib/typeprof/core/ast/method.rb b/lib/typeprof/core/ast/method.rb
index 81e1e125..78f1a7e5 100644
--- a/lib/typeprof/core/ast/method.rb
+++ b/lib/typeprof/core/ast/method.rb
@@ -80,8 +80,15 @@ def self.parse_params(tbl, raw_args, lenv)
         end
       end
 
-      if raw_args.keyword_rest
-        rest_keywords = raw_args.keyword_rest.name
+      case raw_args.keyword_rest
+      when Prism::KeywordRestParameterNode
+        rest_keywords = raw_args.keyword_rest.name if raw_args.keyword_rest
+      when Prism::NoKeywordsParameterNode
+        # what to do?
+      when nil
+        # nothing to do
+      else
+        raise "unexpected keyword rest: #{ raw_args.keyword_rest.class }"
       end
 
       block = raw_args.block.name if raw_args.block
diff --git a/scenario/args/no-keyword.rb b/scenario/args/no-keyword.rb
new file mode 100644
index 00000000..6ad9b1a6
--- /dev/null
+++ b/scenario/args/no-keyword.rb
@@ -0,0 +1,8 @@
+## update
+def check(**nil)
+end
+
+## assert
+class Object
+  def check: -> nil
+end