diff --git a/ext/opencv/pointset.cpp b/ext/opencv/pointset.cpp
index 4d1bc3b..7a3bd1e 100644
--- a/ext/opencv/pointset.cpp
+++ b/ext/opencv/pointset.cpp
@@ -145,17 +145,14 @@ rb_convexity_defects(VALUE self, VALUE hull)
 {
   CvSeq *defects = NULL;
   CvSeq *hull_seq = CVSEQ_WITH_CHECK(hull);
-  CvMemStorage *stg = hull_seq->storage;
+  VALUE storage = cCvMemStorage::new_object();
+  CvMemStorage *storage_ptr = CVMEMSTORAGE(storage);
   try {
-    defects = cvConvexityDefects(CVSEQ(self), hull_seq, stg);
+    defects = cvConvexityDefects(CVSEQ(self), hull_seq, storage_ptr);
   }
   catch (cv::Exception& e) {
     raise_cverror(e);
   }
-  // FIXME: This storage is shared with the argument "hull".
-  // This causes a severe problem that when "hull"'s memory is collected by GC, "defects"'s storage is
-  // also collected.
-  VALUE storage = Data_Wrap_Struct(cCvMemStorage::rb_class(), 0, cCvMemStorage::cvmemstorage_free, stg);
   return cCvSeq::new_sequence(cCvSeq::rb_class(), defects, cCvConvexityDefect::rb_class(), storage);
 }
 
diff --git a/test/test_pointset.rb b/test/test_pointset.rb
index c8d47a2..696ee51 100755
--- a/test/test_pointset.rb
+++ b/test/test_pointset.rb
@@ -71,13 +71,24 @@ class TestPointSet < OpenCVTestCase
   end
 
   def test_convexity_defects
-    flunk('FIXME: Currently PointSet#convexity_defects does not work well.')
     hull = @contour1.convex_hull2(true, false)
     defects = @contour1.convexity_defects(hull)
-    puts defects.class
-    puts defects[0].start.to_a.join(', ')
     assert_equal(CvSeq, defects.class)
     assert_equal(CvConvexityDefect, defects[0].class)
+    assert_equal(32, defects.size)
+
+    d = defects[0]
+    assert_equal(33, d.start.x)
+    assert_equal(57, d.start.y)
+    assert_equal(33, d.depth_point.x)
+    assert_equal(63, d.depth_point.y)
+    assert_equal(32, d.end.x)
+    assert_equal(64, d.end.y)
+    assert_in_delta(0.8485, d.depth, 0.001)
+
+    assert_raise(TypeError) {
+      @contour1.convexity_defects(DUMMY_OBJ)
+    }
   end
 
   def test_min_area_rect2