diff --git a/src/_imaging.c b/src/_imaging.c
index 9a401b9e908..3ffce31e6fd 100644
--- a/src/_imaging.c
+++ b/src/_imaging.c
@@ -3767,9 +3767,9 @@ _compare_pixels(
         // These modes have three channels in four bytes,
         // so we have to ignore the last byte.
 #ifdef WORDS_BIGENDIAN
-        mask = 0xffffff00;
-#else
         mask = 0x00ffffff;
+#else
+        mask = 0xffffff00;
 #endif
     } else if (!strcmp(mode, "LA") || !strcmp(mode, "La") || !strcmp(mode, "PA")) {
         // These modes have two channels in four bytes,