diff --git a/lib/ransack/nodes/grouping.rb b/lib/ransack/nodes/grouping.rb
index 643ffd9..5f6746e 100644
--- a/lib/ransack/nodes/grouping.rb
+++ b/lib/ransack/nodes/grouping.rb
@@ -44,7 +44,7 @@ module Ransack
             self.conditions << condition if condition.valid?
           end
         end
-        self.conditions.uniq!
+        remove_duplicate_conditions!
       end
       alias :c= :conditions=
 
@@ -195,6 +195,17 @@ module Ransack
         Predicate.detect_and_strip_from_string!(string)
         string
       end
+
+      def remove_duplicate_conditions!
+        # If self.conditions.uniq! is called without passing a block, then
+        # conditions differing only by ransacker_args within attributes are
+        # wrongly considered equal and are removed.
+        self.conditions.uniq! do |c|
+          c.attributes.map { |a| [a.name, a.ransacker_args] }.flatten +
+          [c.predicate.name] +
+          c.values.map { |v| v.value }
+        end
+      end
     end
   end
 end
diff --git a/spec/ransack/nodes/grouping_spec.rb b/spec/ransack/nodes/grouping_spec.rb
index 27058f2..6d412c3 100644
--- a/spec/ransack/nodes/grouping_spec.rb
+++ b/spec/ransack/nodes/grouping_spec.rb
@@ -50,6 +50,40 @@ module Ransack
         end
       end
 
+      describe '#conditions=' do
+        let(:conditions) do
+          {
+            "0"=>{
+              "a"=>{"0"=>{"name"=>"name", "ransacker_args"=>""}}, "p"=>"cont", "v"=>{"0"=>{"value"=>"John"}}
+            },
+            "1"=>{
+              "a"=>{"0"=>{"name"=>"name", "ransacker_args"=>""}}, "p"=>"cont", "v"=>{"0"=>{"value"=>"John"}}
+            }
+          }
+        end
+
+        before { subject.conditions = conditions }
+
+        it 'removes duplicates' do
+          expect(subject.conditions.count).to eq 1
+        end
+
+        context 'when conditions differ only by ransacker_args' do
+          let(:conditions) do
+            {
+              "0"=>{
+                "a"=>{"0"=>{"name"=>"with_arguments", "ransacker_args"=>[1,2]}}, "p"=>"eq", "v"=>{"0"=>{"value"=>"10"}}
+              },
+              "1"=>{
+                "a"=>{"0"=>{"name"=>"with_arguments", "ransacker_args"=>[3,4]}}, "p"=>"eq", "v"=>{"0"=>{"value"=>"10"}}
+              }
+            }
+          end
+          it "doesn't consider them duplicates" do
+            expect(subject.conditions.count).to eq 2
+          end
+        end
+      end
     end
   end
 end