diff --git a/buffet/commands/object_schema_unittest.cc b/buffet/commands/object_schema_unittest.cc
index b0332d2..850f64e 100644
--- a/buffet/commands/object_schema_unittest.cc
+++ b/buffet/commands/object_schema_unittest.cc
@@ -536,9 +536,9 @@
 
 TEST(CommandSchema, ObjectPropType_ToJson) {
   buffet::ObjectPropType prop;
-  EXPECT_EQ("{'properties':{}}",
+  EXPECT_EQ("{'additionalProperties':false,'properties':{}}",
             ValueToString(prop.ToJson(false, nullptr).get()));
-  EXPECT_EQ("{'properties':{},'type':'object'}",
+  EXPECT_EQ("{'additionalProperties':false,'properties':{},'type':'object'}",
             ValueToString(prop.ToJson(true, nullptr).get()));
   EXPECT_FALSE(prop.IsBasedOnSchema());
   buffet::ObjectPropType prop2;
@@ -552,10 +552,11 @@
   pw->GetString()->AddLengthConstraint(6, 100);
   schema->AddProp("password", std::move(pw));
   prop2.SetObjectSchema(std::move(schema));
-  EXPECT_EQ("{'properties':{'expires':'integer',"
+  EXPECT_EQ("{'additionalProperties':false,'properties':{'expires':'integer',"
             "'password':{'maxLength':100,'minLength':6}}}",
             ValueToString(prop2.ToJson(false, nullptr).get()));
-  EXPECT_EQ("{'properties':{'expires':{'type':'integer'},"
+  EXPECT_EQ("{'additionalProperties':false,'properties':{"
+            "'expires':{'type':'integer'},"
             "'password':{'maxLength':100,'minLength':6,'type':'string'}},"
             "'type':'object'}",
             ValueToString(prop2.ToJson(true, nullptr).get()));
@@ -566,11 +567,29 @@
       nullptr));
   EXPECT_EQ("{'default':{'expires':3,'password':'abracadabra'}}",
             ValueToString(prop3.ToJson(false, nullptr).get()));
-  EXPECT_EQ("{'default':{'expires':3,'password':'abracadabra'},"
+  EXPECT_EQ("{'additionalProperties':false,"
+            "'default':{'expires':3,'password':'abracadabra'},"
             "'properties':{'expires':{'type':'integer'},"
             "'password':{'maxLength':100,'minLength':6,'type':'string'}},"
             "'type':'object'}",
             ValueToString(prop3.ToJson(true, nullptr).get()));
+
+  buffet::ObjectPropType prop4;
+  ASSERT_TRUE(prop4.FromJson(CreateDictionaryValue(
+      "{'additionalProperties':true,"
+      "'default':{'expires':3,'password':'abracadabra'}}").get(), &prop2,
+      nullptr));
+  EXPECT_EQ("{'additionalProperties':true,"
+            "'default':{'expires':3,'password':'abracadabra'},"
+            "'properties':{'expires':'integer',"
+            "'password':{'maxLength':100,'minLength':6}}}",
+            ValueToString(prop4.ToJson(false, nullptr).get()));
+  EXPECT_EQ("{'additionalProperties':true,"
+            "'default':{'expires':3,'password':'abracadabra'},"
+            "'properties':{'expires':{'type':'integer'},"
+            "'password':{'maxLength':100,'minLength':6,'type':'string'}},"
+            "'type':'object'}",
+            ValueToString(prop4.ToJson(true, nullptr).get()));
 }
 
 TEST(CommandSchema, ObjectPropType_FromJson) {
diff --git a/buffet/commands/prop_types.cc b/buffet/commands/prop_types.cc
index 6365dcc..f60f256 100644
--- a/buffet/commands/prop_types.cc
+++ b/buffet/commands/prop_types.cc
@@ -475,6 +475,9 @@
       }
       dict->SetWithoutPathExpansion(commands::attributes::kObject_Properties,
                                     object_schema.release());
+      dict->SetBooleanWithoutPathExpansion(
+          commands::attributes::kObject_AdditionalProperties,
+          object_schema_.value->GetExtraPropertiesAllowed());
     }
   }
   return value;
@@ -488,6 +491,7 @@
     return false;
 
   using commands::attributes::kObject_Properties;
+  using commands::attributes::kObject_AdditionalProperties;
 
   const ObjectSchema* base_object_schema = nullptr;
   if (base_schema)
@@ -503,11 +507,26 @@
                              "Error parsing object property schema");
       return false;
     }
+    bool extra_properties_allowed = false;
+    if (value->GetBooleanWithoutPathExpansion(kObject_AdditionalProperties,
+                                              &extra_properties_allowed)) {
+      processed_keys->insert(kObject_AdditionalProperties);
+      object_schema->SetExtraPropertiesAllowed(extra_properties_allowed);
+    }
     object_schema_.value = std::move(object_schema);
     object_schema_.is_inherited = false;
   } else if (base_object_schema) {
-    object_schema_.value = base_object_schema->Clone();
-    object_schema_.is_inherited = true;
+    auto cloned_object_schema = base_object_schema->Clone();
+    bool extra_properties_allowed = false;
+    if (value->GetBooleanWithoutPathExpansion(kObject_AdditionalProperties,
+                                              &extra_properties_allowed)) {
+      processed_keys->insert(kObject_AdditionalProperties);
+      cloned_object_schema->SetExtraPropertiesAllowed(extra_properties_allowed);
+      object_schema_.is_inherited = false;
+    } else {
+      object_schema_.is_inherited = true;
+    }
+    object_schema_.value = std::move(cloned_object_schema);
   } else {
     chromeos::Error::AddToPrintf(error, FROM_HERE, errors::commands::kDomain,
                                  errors::commands::kInvalidObjectSchema,
diff --git a/buffet/commands/schema_constants.cc b/buffet/commands/schema_constants.cc
index 3854278..cd06b32 100644
--- a/buffet/commands/schema_constants.cc
+++ b/buffet/commands/schema_constants.cc
@@ -43,6 +43,7 @@
 const char kOneOf_Metadata[] = "metadata";
 
 const char kObject_Properties[] = "properties";
+const char kObject_AdditionalProperties[] = "additionalProperties";
 
 const char kCommand_Id[] = "id";
 const char kCommand_Name[] = "name";
diff --git a/buffet/commands/schema_constants.h b/buffet/commands/schema_constants.h
index 450ad37..6f5ee71 100644
--- a/buffet/commands/schema_constants.h
+++ b/buffet/commands/schema_constants.h
@@ -47,6 +47,7 @@
 extern const char kOneOf_Metadata[];
 
 extern const char kObject_Properties[];
+extern const char kObject_AdditionalProperties[];
 
 extern const char kCommand_Id[];
 extern const char kCommand_Name[];
diff --git a/buffet/states/state_package_unittest.cc b/buffet/states/state_package_unittest.cc
index 9d5b0d6..d2d36e4 100644
--- a/buffet/states/state_package_unittest.cc
+++ b/buffet/states/state_package_unittest.cc
@@ -87,7 +87,7 @@
   EXPECT_EQ(4, GetTypes(package).GetProps().size());
   EXPECT_EQ(4, GetValues(package).size());
   EXPECT_EQ("{'color':{'type':'string'},"
-            "'direction':{'properties':{"
+            "'direction':{'additionalProperties':false,'properties':{"
               "'altitude':{'maximum':90.0,'type':'number'},"
               "'azimuth':{'type':'number'}},"
               "'type':'object'},"
@@ -117,7 +117,7 @@
   EXPECT_EQ(5, GetValues(*package_).size());
   EXPECT_EQ("{'brightness':{'enum':['low','medium','high'],'type':'string'},"
             "'color':{'type':'string'},"
-            "'direction':{'properties':{"
+            "'direction':{'additionalProperties':false,'properties':{"
               "'altitude':{'maximum':90.0,'type':'number'},"
               "'azimuth':{'type':'number'}},"
               "'type':'object'},"