diff --git a/lib/elasticsearch/dsl/search/options.rb b/lib/elasticsearch/dsl/search/options.rb
index d3ca637..b148474 100644
--- a/lib/elasticsearch/dsl/search/options.rb
+++ b/lib/elasticsearch/dsl/search/options.rb
@@ -35,7 +35,8 @@ class Options
           :indices_boost,
           :track_scores,
           :min_score,
-          :track_total_hits
+          :track_total_hits,
+          :runtime_mappings
         ]
 
         def initialize(*args, &block)
diff --git a/test/unit/search_options_test.rb b/test/unit/search_options_test.rb
index 3b07b6c..5d76d7c 100644
--- a/test/unit/search_options_test.rb
+++ b/test/unit/search_options_test.rb
@@ -57,6 +57,11 @@ class SearchOptionsTest < ::Elasticsearch::Test::UnitTestCase
           assert_equal( { script_fields: ['foo'] }, subject.to_hash )
         end
 
+        should "encode runtime_mappings" do
+          subject.runtime_mappings ['foo']
+          assert_equal( { runtime_mappings: ['foo'] }, subject.to_hash )
+        end
+
         should "encode fielddata_fields" do
           subject.fielddata_fields ['foo']
           assert_equal( { fielddata_fields: ['foo'] }, subject.to_hash )