diff --git a/common/jpeg/jdatadst.c b/common/jpeg/jdatadst.c
index a8f6fb0..b874815 100644
--- a/common/jpeg/jdatadst.c
+++ b/common/jpeg/jdatadst.c
@@ -82,8 +82,9 @@
 {
   my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
 
-  if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE) !=
-      (size_t) OUTPUT_BUF_SIZE)
+  if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE
+      - dest->pub.free_in_buffer) !=
+      (size_t) (OUTPUT_BUF_SIZE - dest->pub.free_in_buffer))
     ERREXIT(cinfo, JERR_FILE_WRITE);
 
   dest->pub.next_output_byte = dest->buffer;