diff --git a/activesupport/lib/active_support/core_ext/object/to_param.rb b/activesupport/lib/active_support/core_ext/object/to_param.rb
index e40846e7d677260cf236e76d350903b8c937fa5a..13be0038c23e6a66ff7681c27bf975ee777d91c9 100644
--- a/activesupport/lib/active_support/core_ext/object/to_param.rb
+++ b/activesupport/lib/active_support/core_ext/object/to_param.rb
@@ -51,9 +51,12 @@ class Hash
   #
   # This method is also aliased as +to_query+.
   def to_param(namespace = nil)
-    return (namespace ? nil.to_query(namespace) : '') if empty?
-    collect do |key, value|
-      value.to_query(namespace ? "#{namespace}[#{key}]" : key)
-    end.sort! * '&'
+    if empty?
+      namespace ? nil.to_query(namespace) : ''
+    else
+      collect do |key, value|
+        value.to_query(namespace ? "#{namespace}[#{key}]" : key)
+      end.sort! * '&'
+    end
   end
 end
diff --git a/activesupport/test/core_ext/object/to_query_test.rb b/activesupport/test/core_ext/object/to_query_test.rb
index 51275e36bf7c4dfa1a39bf25f89bc8e487230199..a892471e0f95a9a4b5376bb361634246ad9f60a3 100644
--- a/activesupport/test/core_ext/object/to_query_test.rb
+++ b/activesupport/test/core_ext/object/to_query_test.rb
@@ -47,6 +47,8 @@ def test_array_values_are_not_sorted
   end
 
   def test_nested_empty_hash
+    assert_equal '',
+      {}.to_query
     assert_query_equal 'a=1&b%5Bc%5D=3&b%5Bd%5D=',
       { a: 1, b: { c: 3, d: {} } }
     assert_query_equal 'b%5Bc%5D=false&b%5Be%5D=&b%5Bf%5D=&p=12',