diff --git a/lib/searchkick/query.rb b/lib/searchkick/query.rb
index a207612..da90336 100644
--- a/lib/searchkick/query.rb
+++ b/lib/searchkick/query.rb
@@ -167,14 +167,17 @@ module Searchkick
         custom_filters = []
 
         boost_by = options[:boost_by] || {}
+
         if boost_by.is_a?(Array)
-          boost_by = Hash[boost_by.map { |f| [f, {factor: 1}] }]
+          boost_by_sum = Hash[boost_by.map { |f| [f, {factor: 1}] }]
+        elsif boost_by.is_a?(Hash)
+          boost_by_multiply, boost_by_sum = boost_by.partition { |k,v| v[:boost_mode] == "multiply" }.map{|i| Hash[i] }
         end
         if options[:boost]
-          boost_by[options[:boost]] = {factor: 1}
+          boost_by_sum[options[:boost]] = {factor: 1}
         end
 
-        boost_by.each do |field, value|
+        boost_by_sum.each do |field, value|
           script_score =
             if below12
               {script_score: {script: "#{value[:factor].to_f} * log(doc['#{field}'].value + 2.718281828)"}}
@@ -191,6 +194,28 @@ module Searchkick
           }.merge(script_score)
         end
 
+        if boost_by_multiply
+          multiply_filters = []
+
+          boost_by_multiply.each do |field, value|
+            script_score =
+              if below12
+                {script_score: {script: "#{value[:factor].to_f} * doc['#{field}'].value"}}
+              else
+                value[:factor] ||= 1
+                {field_value_factor: {field: field, factor: value[:factor].to_f}}
+              end
+
+            multiply_filters << {
+              filter: {
+                exists: {
+                  field: field
+                }
+              }
+            }.merge(script_score)
+          end
+        end
+
         boost_where = options[:boost_where] || {}
         if options[:user_id] && personalize_field
           boost_where[personalize_field] = options[:user_id]
@@ -238,31 +263,7 @@ module Searchkick
           }
         end
 
-        multiply_filters = []
-
-        multiply_by = options[:multiply_by] || {}
-        if multiply_by.is_a?(Array)
-          multiply_by = Hash[multiply_by.map { |f| [f, {factor: 1}] }]
-        end
-
-        multiply_by.each do |field, value|
-          script_score =
-            if below12
-              {script_score: {script: "#{value[:factor].to_f} * doc['#{field}'].value"}}
-            else
-              {field_value_factor: {field: field, factor: value[:factor].to_f}}
-            end
-
-          multiply_filters << {
-            filter: {
-              exists: {
-                field: field
-              }
-            }
-          }.merge(script_score)
-        end
-
-        if multiply_filters.any?
+        if multiply_filters && multiply_filters.any?
           payload = {
             function_score: {
               functions: multiply_filters,
diff --git a/test/boost_test.rb b/test/boost_test.rb
index a3f0868..11435ad 100644
--- a/test/boost_test.rb
+++ b/test/boost_test.rb
@@ -108,8 +108,7 @@ class TestBoost < Minitest::Test
       {name: "Tomato C", found_rate: 0.5}
     ]
 
-    assert_order "tomato", ["Tomato B", "Tomato A", "Tomato C"], multiply_by: [:found_rate]
-    assert_order "tomato", ["Tomato B", "Tomato A", "Tomato C"], multiply_by: {found_rate: {factor: 1}}
+    assert_order "tomato", ["Tomato B", "Tomato A", "Tomato C"], boost_by: {found_rate: {factor: 1, boost_mode: "multiply"}}
   end
 
   def test_boost_where
--
libgit2 0.21.0