diff --git a/moviepy/Clip.py b/moviepy/Clip.py
index efdfb22c6..da98764fd 100644
--- a/moviepy/Clip.py
+++ b/moviepy/Clip.py
@@ -264,6 +264,7 @@ def set_end(self, t):
         of the returned clip.
         """
         self.end = t
+        if self.end is None: return
         if self.start is None:
             if self.duration is not None:
                 self.start = max(0, t - newclip.duration)
@@ -387,7 +388,6 @@ def subclip(self, t_start=0, t_end=None):
            t_start = self.duration + t_start   #remeber t_start is negative
 
         if (self.duration is not None) and (t_start>self.duration):
-        
             raise ValueError("t_start (%.02f) "%t_start +
                              "should be smaller than the clip's "+
                              "duration (%.02f)."%self.duration)
diff --git a/moviepy/video/compositing/CompositeVideoClip.py b/moviepy/video/compositing/CompositeVideoClip.py
index 30172b782..e65224864 100644
--- a/moviepy/video/compositing/CompositeVideoClip.py
+++ b/moviepy/video/compositing/CompositeVideoClip.py
@@ -95,7 +95,7 @@ def __init__(self, clips, size=None, bg_color=None, use_bgclip=False,
         # compute mask if necessary
         if transparent:
             maskclips = [(c.mask if (c.mask is not None) else
-                          c.add_mask().mask).set_pos(c.pos)
+                          c.add_mask().mask).set_pos(c.pos).set_end(c.end).set_start(c.start, change_end=False)
                           for c in self.clips]
 
             self.mask = CompositeVideoClip(maskclips,self.size, ismask=True,
diff --git a/tests/test_TextClip.py b/tests/test_TextClip.py
index b07605c7b..41932d8b8 100644
--- a/tests/test_TextClip.py
+++ b/tests/test_TextClip.py
@@ -15,7 +15,7 @@ def test_duration():
        return
     
     clip = TextClip('hello world', size=(1280,720), color='white')
-    clip.set_duration(5)
+    clip=clip.set_duration(5)
     assert clip.duration == 5
 
     clip2 = clip.fx(blink, d_on=1, d_off=1)
diff --git a/tests/test_issues.py b/tests/test_issues.py
index c125b8faf..c819ca6ee 100644
--- a/tests/test_issues.py
+++ b/tests/test_issues.py
@@ -266,6 +266,19 @@ def test_audio_reader():
         subclip.write_audiofile(os.path.join(TMP_DIR, 'issue_246.wav'),
                                 write_logfile=True)
 
+def test_issue_547():
+    red = ColorClip((640, 480), color=(255,0,0)).set_duration(1)
+    green = ColorClip((640, 480), color=(0,255,0)).set_duration(2)
+    blue = ColorClip((640, 480), color=(0,0,255)).set_duration(3)
+
+    video=concatenate_videoclips([red, green, blue], method="compose")
+    assert video.duration == 6
+    assert video.mask.duration == 6
+
+    video=concatenate_videoclips([red, green, blue])
+    assert video.duration == 6
+
 
 if __name__ == '__main__':
    pytest.main()
+