diff --git a/src/libImaging/Convert.c b/src/libImaging/Convert.c
index ba57deca1..5dc17db60 100644
--- a/src/libImaging/Convert.c
+++ b/src/libImaging/Convert.c
@@ -1031,7 +1031,7 @@ p2pa(UINT8 *out, const UINT8 *in, int xsize, ImagingPalette palette) {
     int x;
     int rgb = strcmp(palette->mode, "RGB");
     for (x = 0; x < xsize; x++, in++) {
-        const UINT8 *rgba = &palette->palette[in[0]];
+        const UINT8 *rgba = &palette->palette[in[0] * 4];
         *out++ = in[0];
         *out++ = in[0];
         *out++ = in[0];