diff --git a/lib/ast_to_prism/parser.rb b/lib/ast_to_prism/parser.rb
index 6cfc3cb..2829c91 100644
--- a/lib/ast_to_prism/parser.rb
+++ b/lib/ast_to_prism/parser.rb
@@ -823,7 +823,7 @@ def convert_node(node, block: nil)
       when :CASE3
         not_supported(node)
       when :WHEN
-        not_supported(node)
+        not_expected(node)
       when :IN
         not_supported(node)
       when :WHILE
@@ -1781,7 +1781,7 @@ def convert_node(node, block: nil)
           location(node) # location
         )
       when :ONCE
-        not_supported(node)
+        not_expected(node)
       when :DSTR
         not_supported(node)
       when :DXSTR