diff --git a/examples/png2theora.c b/examples/png2theora.c
index 281c8acb0eb3cd4f7c13955755bb36f0fd39302a..c740ad8043848738909c09b07135d7cedb9e5fff 100644
--- a/examples/png2theora.c
+++ b/examples/png2theora.c
@@ -331,7 +331,7 @@ rgb_to_yuv(png_bytep *png,
 
         yuv_u[(x >> 1) + (y >> 1) * ycbcr[1].stride] =
           clamp( ((-33488*r0-65744*g0+99232*b0+29032005)/4 +
-                  (-33488*r0-65744*g0+99232*b0+29032005)/4 +
+                  (-33488*r1-65744*g1+99232*b1+29032005)/4 +
                   (-33488*r2-65744*g2+99232*b2+29032005)/4 +
                   (-33488*r3-65744*g3+99232*b3+29032005)/4)/225930);
         yuv_v[(x >> 1) + (y >> 1) * ycbcr[2].stride] =