diff --git a/pd/src/d_soundfile.c b/pd/src/d_soundfile.c
index 95d2736562a87dafbd7a74572bafa78171cb68d8..0cf6de4c2790cea428400341ad9d2892b2115781 100644
--- a/pd/src/d_soundfile.c
+++ b/pd/src/d_soundfile.c
@@ -375,7 +375,7 @@ int open_soundfile_via_fd(int fd, int headersize,
                 headersize = seekto;
             }
             bytelimit = swap4(((t_datachunk *)buf)->dc_size, swap);
-            headersize += 8;
+            headersize += sizeof(t_datachunk);
         }
     }
         /* seek past header and any sample frames to skip */