Must support -mattecolor option for IMv6 compatibility.
diff --git a/coders/json.c b/coders/json.c
index 662138d..9ac1252 100644
--- a/coders/json.c
+++ b/coders/json.c
@@ -1205,8 +1205,8 @@
       "      \"x\": %.20g,\n      \"y\": %.20g\n    },\n",
       (double) image->extract_info.width,(double) image->extract_info.height,
       (double) image->extract_info.x,(double) image->extract_info.y);
-  GetColorTuple(&image->alpha_color,MagickTrue,color);
-  (void) FormatLocaleFile(file,"    \"alphaColor\": \"%s\",\n",color);
+  GetColorTuple(&image->matte_color,MagickTrue,color);
+  (void) FormatLocaleFile(file,"    \"matteColor\": \"%s\",\n",color);
   GetColorTuple(&image->background_color,MagickTrue,color);
   (void) FormatLocaleFile(file,"    \"backgroundColor\": \"%s\",\n",color);
   GetColorTuple(&image->border_color,MagickTrue,color);