diff --git a/lib/xlsxtream/io/hash.rb b/lib/xlsxtream/io/hash.rb
index e402c1c..2574f66 100644
--- a/lib/xlsxtream/io/hash.rb
+++ b/lib/xlsxtream/io/hash.rb
@@ -38,7 +38,7 @@ def [](path)
       end
 
       def to_h
-        @hash.keys.map {|path| [path, fetch(path)] }.to_h
+        ::Hash[@hash.keys.map {|path| [path, fetch(path)] }]
       end
     end
   end