diff --git a/tests/unit/base/MockObject.h b/tests/unit/base/MockObject.h
index 7f44cafccd7..d043850f695 100644
--- a/tests/unit/base/MockObject.h
+++ b/tests/unit/base/MockObject.h
@@ -83,6 +83,9 @@ namespace shogun
 			watch_param("object", &m_object);
 			m_parameters->add(
 			    (CSGObject**)&m_object, "object", "The object (tm)");
+
+			m_string = "Shogun rocks!";
+			watch_param("string", &m_string);
 		}
 
 		void free_single()
@@ -246,6 +249,8 @@ namespace shogun
 		T* m_raw_matrix_basic;
 		index_t m_raw_matrix_basic_rows;
 		index_t m_raw_matrix_basic_cols;
+
+		std::string m_string;
 	};
 
 	/** @brief Used to test the tags-parameter framework
diff --git a/tests/unit/base/SGObject_unittest.cc b/tests/unit/base/SGObject_unittest.cc
index 787c34f9d1d..32d80f7dec4 100644
--- a/tests/unit/base/SGObject_unittest.cc
+++ b/tests/unit/base/SGObject_unittest.cc
@@ -78,6 +78,16 @@ TYPED_TEST(SGObjectEquals, different_basic)
 	EXPECT_FALSE(obj2->equals(obj1));
 }
 
+TYPED_TEST(SGObjectEquals, different_string)
+{
+	auto obj1 = some<CCloneEqualsMock<TypeParam>>();
+	auto obj2 = some<CCloneEqualsMock<TypeParam>>();
+
+	obj1->m_string = "Oh no!";
+	EXPECT_FALSE(obj1->equals(obj2));
+	EXPECT_FALSE(obj2->equals(obj1));
+}
+
 TYPED_TEST(SGObjectEquals, different_object)
 {
 	auto obj1 = some<CCloneEqualsMock<TypeParam>>();
@@ -221,6 +231,7 @@ TYPED_TEST(SGObjectClone, equals_non_empty)
 {
 	auto obj = some<CCloneEqualsMock<TypeParam>>();
 	obj->m_basic -= 1;
+	obj->m_string = "Non empty string";
 	obj->m_object->m_some_value -= 1;
 	obj->m_sg_vector[0] -= 1;
 	obj->m_sg_matrix(0, 0) = 0;