diff --git a/lib/ransack/search.rb b/lib/ransack/search.rb
index 03115c5a..4d196a2b 100644
--- a/lib/ransack/search.rb
+++ b/lib/ransack/search.rb
@@ -26,7 +26,7 @@ def initialize(object, params = {}, options = {})
       if params.is_a? Hash
         params = params.dup
         params = params.transform_values { |v| v.is_a?(String) && strip_whitespace ? v.strip : v }
-        params.delete_if { |k, v| [*v].all?{ |i| i.blank? && i != false } }
+        params.delete_if { |k, v| [*v].all?{ |i| i.blank? && i != false && !i.nil? } }
       else
         params = {}
       end
diff --git a/spec/ransack/search_spec.rb b/spec/ransack/search_spec.rb
index d7fd1c86..3709f7ce 100644
--- a/spec/ransack/search_spec.rb
+++ b/spec/ransack/search_spec.rb
@@ -75,6 +75,12 @@ module Ransack
         Search.new(Person, name_eq_any: ['foobar'])
       end
 
+      it 'keeps conditions with a nil value in an array before building' do
+        expect_any_instance_of(Search).to receive(:build)
+        .with({ 'name_in' => [nil] })
+        Search.new(Person, name_in: [nil])
+      end
+
       it 'does not raise exception for string :params argument' do
         expect { Search.new(Person, '') }.not_to raise_error
       end