diff --git a/magick/morphology.c b/magick/morphology.c
index e9e793e..40a512a 100644
--- a/magick/morphology.c
+++ b/magick/morphology.c
@@ -1761,11 +1761,11 @@
case TopHatMorphology:
case BottomHatMorphology:
/* Get Difference relative to the original image */
- CompositeImageChannel(new_image, channel, DifferenceCompositeOp,
+ (void) CompositeImageChannel(new_image, channel, DifferenceCompositeOp,
image, 0, 0);
break;
case EdgeMorphology: /* subtract the Erode from a Dilate */
- CompositeImageChannel(new_image, channel, DifferenceCompositeOp,
+ (void) CompositeImageChannel(new_image, channel, DifferenceCompositeOp,
grad_image, 0, 0);
grad_image=DestroyImage(grad_image);
break;