diff --git a/dnssec-tools/validator/libsres/res_io_manager.c b/dnssec-tools/validator/libsres/res_io_manager.c
index 810fb0f..edfb46a 100644
--- a/dnssec-tools/validator/libsres/res_io_manager.c
+++ b/dnssec-tools/validator/libsres/res_io_manager.c
@@ -1234,7 +1234,7 @@ complete_read(SOCKET sock, u_char *field, size_t length)
break;
}
bytes_read += bytes;
- } while (bytes_read < length);
+ } while (bytes_read < length && bytes != 0);
return bytes_read;
}