diff --git a/libmpeg2/libmpeg-0.4.0.diff b/libmpeg2/libmpeg-0.4.0.diff
index 1b02c21749..fb93fe0997 100644
--- a/libmpeg2/libmpeg-0.4.0.diff
+++ b/libmpeg2/libmpeg-0.4.0.diff
@@ -377,13 +377,22 @@
  
      decoder->quantizer_matrix[0] =
  	decoder->quantizer_prescale[0][quantizer_scale_code];
-@@ -1564,6 +1569,9 @@
+@@ -1568,6 +1569,18 @@
  
  #define NEXT_MACROBLOCK							\
  do {									\
-+    if(decoder->quant_store)                                            \
++    if(decoder->quant_store) {                                          \
++       if (decoder->picture_structure == TOP_FIELD)                     \
++        decoder->quant_store[2*decoder->quant_stride*(decoder->v_offset>>4) \
++                    +(decoder->offset>>4)] = decoder->quantizer_scale;  \
++       else if (decoder->picture_structure == BOTTOM_FIELD)             \
++        decoder->quant_store[2*decoder->quant_stride*(decoder->v_offset>>4) \
++	            + decoder->quant_stride                             \
++                    +(decoder->offset>>4)] = decoder->quantizer_scale;  \
++       else                                                             \
 +        decoder->quant_store[decoder->quant_stride*(decoder->v_offset>>4) \
 +                    +(decoder->offset>>4)] = decoder->quantizer_scale;  \
++    }                                                                   \
      decoder->offset += 16;						\
      if (decoder->offset == decoder->width) {				\
  	do { /* just so we can use the break statement */		\