diff --git a/miniz_zip.c b/miniz_zip.c
index 3a56479..e38f437 100644
--- a/miniz_zip.c
+++ b/miniz_zip.c
@@ -3466,7 +3466,7 @@ mz_bool mz_zip_writer_add_mem_ex_v2(mz_zip_archive *pZip, const char *pArchive_n
 mz_bool mz_zip_writer_add_read_buf_callback(mz_zip_archive *pZip, const char *pArchive_name, mz_file_read_func read_callback, void* callback_opaque, mz_uint64 max_size, const MZ_TIME_T *pFile_time, const void *pComment, mz_uint16 comment_size, mz_uint level_and_flags,
                                 const char *user_extra_data, mz_uint user_extra_data_len, const char *user_extra_data_central, mz_uint user_extra_data_central_len)
 {
-    mz_uint16 gen_flags = (level_and_flags & MZ_ZIP_FLAG_WRITE_HEADER_SET_SIZE) ? 0 : MZ_ZIP_LDH_BIT_FLAG_HAS_LOCATOR;
+    mz_uint16 gen_flags;
     mz_uint uncomp_crc32 = MZ_CRC32_INIT, level, num_alignment_padding_bytes;
     mz_uint16 method = 0, dos_time = 0, dos_date = 0, ext_attributes = 0;
     mz_uint64 local_dir_header_ofs, cur_archive_file_ofs = pZip->m_archive_size, uncomp_size = 0, comp_size = 0;
@@ -3485,6 +3485,8 @@ mz_bool mz_zip_writer_add_read_buf_callback(mz_zip_archive *pZip, const char *pA
         level_and_flags = MZ_DEFAULT_LEVEL;
     level = level_and_flags & 0xF;
 
+    gen_flags = (level_and_flags & MZ_ZIP_FLAG_WRITE_HEADER_SET_SIZE) ? 0 : MZ_ZIP_LDH_BIT_FLAG_HAS_LOCATOR;
+
     /* Sanity checks */
     if ((!pZip) || (!pZip->m_pState) || (pZip->m_zip_mode != MZ_ZIP_MODE_WRITING) || (!pArchive_name) || ((comment_size) && (!pComment)) || (level > MZ_UBER_COMPRESSION))
         return mz_zip_set_error(pZip, MZ_ZIP_INVALID_PARAMETER);