diff --git a/coders/jp2.c b/coders/jp2.c
index 5585cff..a70d091 100644
--- a/coders/jp2.c
+++ b/coders/jp2.c
@@ -581,8 +581,8 @@
           SetBluePixelComponent(q,ScaleAnyToQuantum((QuantumAny) pixel,
             range[2]));
           pixel=(QuantumAny) jas_matrix_getv(pixels[3],x/x_step[3]);
-          SetOpacityPixelComponent(q,(QuantumRange-
-            ScaleAnyToQuantum((QuantumAny) pixel,range[3])));
+          SetAlphaPixelComponent(q,ScaleAnyToQuantum((QuantumAny) pixel,
+            range[3]));
           q++;
         }
         break;