diff --git a/lib/enummer/extension.rb b/lib/enummer/extension.rb
index 7fe20a6..a48fae4 100644
--- a/lib/enummer/extension.rb
+++ b/lib/enummer/extension.rb
@@ -38,11 +38,12 @@ def _enummer_build_values(attribute_name, value_names, options)
 
         define_method("#{method_name}?") { self[attribute_name].include?(name) }
         define_method("#{method_name}=") do |new_value|
-          if new_value
-            self[attribute_name].push(name)
+          if ActiveModel::Type::Boolean.new.cast(new_value)
+            self[attribute_name] += [name]
           else
-            self[attribute_name].delete(name)
+            self[attribute_name] -= [name]
           end
+          self[attribute_name].uniq!
         end
         define_method("#{method_name}!") do
           update(attribute_name => self[attribute_name] + [name])
diff --git a/test/enummer_test.rb b/test/enummer_test.rb
index ba5bb58..11b3d2a 100644
--- a/test/enummer_test.rb
+++ b/test/enummer_test.rb
@@ -57,12 +57,20 @@ def setup
     @user3.read = true
 
     assert_equal %i[execute read], @user3.permissions
+
+    @user3.save
+
+    assert_equal %i[execute read].sort, @user3.permissions.sort
   end
 
   test "setting a setter to false removes the value" do
     @user1.write = false
 
     assert_equal %i[read execute], @user1.permissions
+
+    @user1.save
+
+    assert_equal %i[read execute].sort, @user1.permissions.sort
   end
 
   test "setting the attribute with strings adds the values" do
@@ -88,6 +96,18 @@ def setup
     refute @user1.consumes_greens?
   end
 
+  test "update with prefix" do
+    assert @user1.consumes_cigarettes?
+    refute @user1.consumes_greens?
+    @user1.update!(consumes_cigarettes: true)
+    refute @user1.consumes_greens?
+  end
+
+  test "recognizes boolean params" do
+    @user1.update!(ActionController::Parameters.new({"consumes_cigarettes"=>"false"}).permit(:consumes_cigarettes))
+    refute @user1.consumes_cigarettes?
+  end
+
   test "methods respect _suffix" do
     refute @user1.car_transport?
     refute @user1.truck_transport?