diff --git a/lib/mongo/util/ordered_hash.rb b/lib/mongo/util/ordered_hash.rb
index 209f4e5..0448eb6 100644
--- a/lib/mongo/util/ordered_hash.rb
+++ b/lib/mongo/util/ordered_hash.rb
@@ -53,7 +53,7 @@ class OrderedHash < Hash
 
   def inspect
     str = '{'
-    str << @ordered_keys.collect { |k| "\"#{k}\"=>#{self.[](k).inspect}" }.join(", ")
+    str << (@ordered_keys || []).collect { |k| "\"#{k}\"=>#{self.[](k).inspect}" }.join(", ")
     str << '}'
   end