diff --git a/g10/build-packet.c b/g10/build-packet.c
index 19a13760a..8b5b20af4 100644
--- a/g10/build-packet.c
+++ b/g10/build-packet.c
@@ -993,9 +993,16 @@ do_plaintext( IOBUF out, int ctb, PKT_plaintext *pt )
         if (nbytes == (size_t)(-1)
             && (iobuf_error (out) || iobuf_error (pt->buf)))
             return iobuf_error (out)? iobuf_error (out):iobuf_error (pt->buf);
-        /* Always get the error to catch write errors because
-         * iobuf_copy does not reliable return (-1) in that case.  */
-        rc = iobuf_error (out);
+        else if (nbytes != (size_t)(-1) && iobuf_error (pt->buf))
+          rc = iobuf_error (pt->buf);  /* Read error.  */
+        else
+          {
+            /* Always get the iobuf error to catch write errors
+             * because iobuf_copy returns (-1) only if there was a
+             * errors in the output stream when entering that
+             * function.  */
+            rc = iobuf_error (out);
+          }
         if(ctb_new_format_p (ctb) && !pt->len)
           /* Turn off partial body length mode.  */
           iobuf_set_partial_body_length_mode (out, 0);