diff --git a/src/miniz.h b/src/miniz.h
index ab29b11..a1a171d 100644
--- a/src/miniz.h
+++ b/src/miniz.h
@@ -1356,6 +1356,12 @@ MINIZ_EXPORT mz_bool mz_zip_reader_init_file_v2(mz_zip_archive *pZip,
                                                 mz_uint flags,
                                                 mz_uint64 file_start_ofs,
                                                 mz_uint64 archive_size);
+MINIZ_EXPORT mz_bool mz_zip_reader_init_file_v2_rpb(mz_zip_archive *pZip,
+                                                const char *pFilename,
+                                                mz_uint flags,
+                                                mz_uint64 file_start_ofs,
+                                                mz_uint64 archive_size);
+
 
 /* Read an archive from an already opened FILE, beginning at the current file
  * position. */
@@ -1619,6 +1625,9 @@ MINIZ_EXPORT mz_bool mz_zip_writer_init_from_reader(mz_zip_archive *pZip,
 MINIZ_EXPORT mz_bool mz_zip_writer_init_from_reader_v2(mz_zip_archive *pZip,
                                                        const char *pFilename,
                                                        mz_uint flags);
+MINIZ_EXPORT mz_bool mz_zip_writer_init_from_reader_v2_noreopen(mz_zip_archive *pZip,
+                                                       const char *pFilename,
+                                                       mz_uint flags);
 
 /* Adds the contents of a memory buffer to an archive. These functions record
  * the current local time into the archive. */
@@ -5966,6 +5975,59 @@ mz_bool mz_zip_reader_init_file_v2(mz_zip_archive *pZip, const char *pFilename,
   return MZ_TRUE;
 }
 
+mz_bool mz_zip_reader_init_file_v2_rpb(mz_zip_archive *pZip, const char *pFilename,
+                                   mz_uint flags, mz_uint64 file_start_ofs,
+                                   mz_uint64 archive_size) {
+  mz_uint64 file_size;
+  MZ_FILE *pFile;
+
+  if ((!pZip) || (!pFilename) ||
+      ((archive_size) &&
+       (archive_size < MZ_ZIP_END_OF_CENTRAL_DIR_HEADER_SIZE)))
+    return mz_zip_set_error(pZip, MZ_ZIP_INVALID_PARAMETER);
+
+  pFile = MZ_FOPEN(pFilename, "r+b");
+  if (!pFile)
+    return mz_zip_set_error(pZip, MZ_ZIP_FILE_OPEN_FAILED);
+
+  file_size = archive_size;
+  if (!file_size) {
+    if (MZ_FSEEK64(pFile, 0, SEEK_END)) {
+      MZ_FCLOSE(pFile);
+      return mz_zip_set_error(pZip, MZ_ZIP_FILE_SEEK_FAILED);
+    }
+
+    file_size = MZ_FTELL64(pFile);
+  }
+
+  /* TODO: Better sanity check archive_size and the # of actual remaining bytes
+   */
+
+  if (file_size < MZ_ZIP_END_OF_CENTRAL_DIR_HEADER_SIZE) {
+    MZ_FCLOSE(pFile);
+    return mz_zip_set_error(pZip, MZ_ZIP_NOT_AN_ARCHIVE);
+  }
+
+  if (!mz_zip_reader_init_internal(pZip, flags)) {
+    MZ_FCLOSE(pFile);
+    return MZ_FALSE;
+  }
+
+  pZip->m_zip_type = MZ_ZIP_TYPE_FILE;
+  pZip->m_pRead = mz_zip_file_read_func;
+  pZip->m_pIO_opaque = pZip;
+  pZip->m_pState->m_pFile = pFile;
+  pZip->m_archive_size = file_size;
+  pZip->m_pState->m_file_archive_start_ofs = file_start_ofs;
+
+  if (!mz_zip_reader_read_central_dir(pZip, flags)) {
+    mz_zip_reader_end_internal(pZip, MZ_FALSE);
+    return MZ_FALSE;
+  }
+
+  return MZ_TRUE;
+}
+
 mz_bool mz_zip_reader_init_cfile(mz_zip_archive *pZip, MZ_FILE *pFile,
                                  mz_uint64 archive_size, mz_uint flags) {
   mz_uint64 cur_file_ofs;
@@ -7992,6 +8054,88 @@ mz_bool mz_zip_writer_init_from_reader_v2(mz_zip_archive *pZip,
   return MZ_TRUE;
 }
 
+mz_bool mz_zip_writer_init_from_reader_v2_noreopen(mz_zip_archive *pZip,
+                                          const char *pFilename,
+                                          mz_uint flags) {
+  mz_zip_internal_state *pState;
+
+  if ((!pZip) || (!pZip->m_pState) || (pZip->m_zip_mode != MZ_ZIP_MODE_READING))
+    return mz_zip_set_error(pZip, MZ_ZIP_INVALID_PARAMETER);
+
+  if (flags & MZ_ZIP_FLAG_WRITE_ZIP64) {
+    /* We don't support converting a non-zip64 file to zip64 - this seems like
+     * more trouble than it's worth. (What about the existing 32-bit data
+     * descriptors that could follow the compressed data?) */
+    if (!pZip->m_pState->m_zip64)
+      return mz_zip_set_error(pZip, MZ_ZIP_INVALID_PARAMETER);
+  }
+
+  /* No sense in trying to write to an archive that's already at the support max
+   * size */
+  if (pZip->m_pState->m_zip64) {
+    if (pZip->m_total_files == MZ_UINT32_MAX)
+      return mz_zip_set_error(pZip, MZ_ZIP_TOO_MANY_FILES);
+  } else {
+    if (pZip->m_total_files == MZ_UINT16_MAX)
+      return mz_zip_set_error(pZip, MZ_ZIP_TOO_MANY_FILES);
+
+    if ((pZip->m_archive_size + MZ_ZIP_CENTRAL_DIR_HEADER_SIZE +
+         MZ_ZIP_LOCAL_DIR_HEADER_SIZE) > MZ_UINT32_MAX)
+      return mz_zip_set_error(pZip, MZ_ZIP_FILE_TOO_LARGE);
+  }
+
+  pState = pZip->m_pState;
+
+  if (pState->m_pFile) {
+#ifdef MINIZ_NO_STDIO
+    (void)pFilename;
+    return mz_zip_set_error(pZip, MZ_ZIP_INVALID_PARAMETER);
+#else
+    if (pZip->m_pIO_opaque != pZip)
+      return mz_zip_set_error(pZip, MZ_ZIP_INVALID_PARAMETER);
+
+    if (pZip->m_zip_type == MZ_ZIP_TYPE_FILE) {
+      if (!pFilename)
+        return mz_zip_set_error(pZip, MZ_ZIP_INVALID_PARAMETER);
+    }
+
+    pZip->m_pWrite = mz_zip_file_write_func;
+    pZip->m_pNeeds_keepalive = NULL;
+#endif /* #ifdef MINIZ_NO_STDIO */
+  } else if (pState->m_pMem) {
+    /* Archive lives in a memory block. Assume it's from the heap that we can
+     * resize using the realloc callback. */
+    if (pZip->m_pIO_opaque != pZip)
+      return mz_zip_set_error(pZip, MZ_ZIP_INVALID_PARAMETER);
+
+    pState->m_mem_capacity = pState->m_mem_size;
+    pZip->m_pWrite = mz_zip_heap_write_func;
+    pZip->m_pNeeds_keepalive = NULL;
+  }
+  /* Archive is being read via a user provided read function - make sure the
+     user has specified a write function too. */
+  else if (!pZip->m_pWrite)
+    return mz_zip_set_error(pZip, MZ_ZIP_INVALID_PARAMETER);
+
+  /* Start writing new files at the archive's current central directory
+   * location. */
+  /* TODO: We could add a flag that lets the user start writing immediately
+   * AFTER the existing central dir - this would be safer. */
+  pZip->m_archive_size = pZip->m_central_directory_file_ofs;
+  pZip->m_central_directory_file_ofs = 0;
+
+  /* Clear the sorted central dir offsets, they aren't useful or maintained now.
+   */
+  /* Even though we're now in write mode, files can still be extracted and
+   * verified, but file locates will be slow. */
+  /* TODO: We could easily maintain the sorted central directory offsets. */
+  mz_zip_array_clear(pZip, &pZip->m_pState->m_sorted_central_dir_offsets);
+
+  pZip->m_zip_mode = MZ_ZIP_MODE_WRITING;
+
+  return MZ_TRUE;
+}
+
 mz_bool mz_zip_writer_init_from_reader(mz_zip_archive *pZip,
                                        const char *pFilename) {
   return mz_zip_writer_init_from_reader_v2(pZip, pFilename, 0);
@@ -8560,7 +8704,7 @@ mz_bool mz_zip_writer_add_read_buf_callback(
 
   pState = pZip->m_pState;
   cur_archive_file_ofs = pZip->m_archive_size;
-  
+
   if ((!pState->m_zip64) && (max_size > MZ_UINT32_MAX)) {
     /* Source file is too large for non-zip64 */
     /*return mz_zip_set_error(pZip, MZ_ZIP_ARCHIVE_TOO_LARGE); */
diff --git a/src/zip.c b/src/zip.c
index 82e77c9..b5b219b 100644
--- a/src/zip.c
+++ b/src/zip.c
@@ -822,17 +822,18 @@ struct zip_t *zip_open(const char *zipname, int level, char mode) {
   case 'r':
   case 'a':
   case 'd':
-    if (!mz_zip_reader_init_file(
+    if (!mz_zip_reader_init_file_v2_rpb(
             &(zip->archive), zipname,
-            zip->level | MZ_ZIP_FLAG_DO_NOT_SORT_CENTRAL_DIRECTORY)) {
+            zip->level | MZ_ZIP_FLAG_DO_NOT_SORT_CENTRAL_DIRECTORY, 0, 0)) {
       // An archive file does not exist or cannot initialize
       // zip_archive reader
       goto cleanup;
     }
-    if ((mode == 'a' || mode == 'd') &&
-        !mz_zip_writer_init_from_reader(&(zip->archive), zipname)) {
-      mz_zip_reader_end(&(zip->archive));
-      goto cleanup;
+    if ((mode == 'a' || mode == 'd')) {
+      if (!mz_zip_writer_init_from_reader_v2_noreopen(&(zip->archive), zipname, 0)) {
+        mz_zip_reader_end(&(zip->archive));
+        goto cleanup;
+      }
     }
     break;
 
diff --git a/test/test_append.c b/test/test_append.c
index 5faf2d4..d79c4dc 100644
--- a/test/test_append.c
+++ b/test/test_append.c
@@ -24,7 +24,9 @@ void test_setup(void) {
   zip_close(zip);
 }
 
-void test_teardown(void) { remove(ZIPNAME); }
+void test_teardown(void) {
+  remove(ZIPNAME);
+}
 
 #define TESTDATA2 "Some test data 2...\0"
 #define CRC32DATA2 2532008468
@@ -41,7 +43,9 @@ MU_TEST(test_append) {
   mu_check(CRC32DATA2 == zip_entry_crc32(zip));
   mu_assert_int_eq(0, zip_entry_close(zip));
   ++total_entries;
+  zip_close(zip);
 
+  zip = zip_open(ZIPNAME, ZIP_DEFAULT_COMPRESSION_LEVEL, 'a');
   mu_assert_int_eq(0, zip_entry_open(zip, "test\\empty/"));
   mu_assert_int_eq(0, strcmp(zip_entry_name(zip), "test/empty/"));
   mu_assert_int_eq(0, zip_entry_size(zip));
@@ -49,7 +53,9 @@ MU_TEST(test_append) {
   mu_assert_int_eq(total_entries, zip_entry_index(zip));
   mu_assert_int_eq(0, zip_entry_close(zip));
   ++total_entries;
+  zip_close(zip);
 
+  zip = zip_open(ZIPNAME, ZIP_DEFAULT_COMPRESSION_LEVEL, 'a');
   mu_assert_int_eq(0, zip_entry_open(zip, "empty/"));
   mu_assert_int_eq(0, strcmp(zip_entry_name(zip), "empty/"));
   mu_assert_int_eq(0, zip_entry_size(zip));