diff --git a/src/read.c b/src/read.c
index ccc02d0..97246ce 100644
--- a/src/read.c
+++ b/src/read.c
@@ -2518,6 +2518,7 @@
             }
 
             avifImageStealPlanes(decoder->image, srcAlpha, AVIF_PLANES_A);
+            decoder->image->alphaRange = srcAlpha->alphaRange;
         }
     }