diff --git a/src/column.js b/src/column.js
index 1ba1b41..3ffd884 100644
--- a/src/column.js
+++ b/src/column.js
@@ -1,9 +1,8 @@
 import { unconvert } from './unconvert.js'
-import { writeRleBitPackedHybrid } from './encoding.js'
 import { writePlain } from './plain.js'
 import { snappyCompress } from './snappy.js'
 import { ByteWriter } from './bytewriter.js'
-import { writeLevels, writePageHeader } from './datapage.js'
+import { writeDataPageV2, writePageHeader } from './datapage.js'
 
 /**
  * @param {Writer} writer
@@ -23,77 +22,39 @@ export function writeColumn(writer, schemaPath, values, compressed, stats) {
   // Compute statistics
   const statistics = stats ? getStatistics(values) : undefined
 
-  // Write levels to temp buffer
-  const levels = new ByteWriter()
-  const { definition_levels_byte_length, repetition_levels_byte_length, num_nulls }
-    = writeLevels(levels, schemaPath, values)
-
   // dictionary encoding
   let dictionary_page_offset = undefined
+  let data_page_offset = BigInt(writer.offset)
   /** @type {DecodedArray | undefined} */
   const dictionary = useDictionary(values, type)
   if (dictionary) {
     dictionary_page_offset = BigInt(writer.offset)
 
     // replace values with dictionary indices
-    const indexes = new Int32Array(values.length)
+    const indexes = new Array(values.length)
     for (let i = 0; i < values.length; i++) {
-      indexes[i] = dictionary.indexOf(values[i])
+      if (values[i] !== null && values[i] !== undefined) {
+        indexes[i] = dictionary.indexOf(values[i])
+      }
     }
-    values = indexes
 
     // write unconverted dictionary page
     const unconverted = unconvert(schemaElement, dictionary)
     writeDictionaryPage(writer, unconverted, type, compressed)
+
+    // write data page with dictionary indexes
+    data_page_offset = BigInt(writer.offset)
+    writeDataPageV2(writer, indexes, type, schemaPath, 'RLE_DICTIONARY', compressed)
   } else {
-    // unconvert type and filter out nulls
+    // unconvert values from rich types to simple
     values = unconvert(schemaElement, values)
-      .filter(v => v !== null && v !== undefined)
+
+    // write data page
+    writeDataPageV2(writer, values, type, schemaPath, 'PLAIN', compressed)
   }
 
-  // write page data to temp buffer
-  const page = new ByteWriter()
   /** @type {import('hyparquet').Encoding} */
   const encoding = dictionary ? 'RLE_DICTIONARY' : 'PLAIN'
-  if (dictionary) {
-    const bitWidth = Math.ceil(Math.log2(dictionary.length))
-    page.appendUint8(bitWidth)
-    writeRleBitPackedHybrid(page, values)
-  } else {
-    writePlain(page, values, type)
-  }
-
-  // compress page data
-  let compressedPage = page
-  if (compressed) {
-    compressedPage = new ByteWriter()
-    snappyCompress(compressedPage, new Uint8Array(page.getBuffer()))
-  }
-
-  // write page header
-  const data_page_offset = BigInt(writer.offset)
-  /** @type {PageHeader} */
-  const header = {
-    type: 'DATA_PAGE_V2',
-    uncompressed_page_size: levels.offset + page.offset,
-    compressed_page_size: levels.offset + compressedPage.offset,
-    data_page_header_v2: {
-      num_values,
-      num_nulls,
-      num_rows: num_values,
-      encoding: dictionary ? 'RLE_DICTIONARY' : encoding,
-      definition_levels_byte_length,
-      repetition_levels_byte_length,
-      is_compressed: true,
-    },
-  }
-  writePageHeader(writer, header)
-
-  // write levels
-  writer.appendBuffer(levels.getBuffer())
-
-  // write page data
-  writer.appendBuffer(compressedPage.getBuffer())
 
   return {
     type,
diff --git a/src/datapage.js b/src/datapage.js
index 953b2b8..bfc9b90 100644
--- a/src/datapage.js
+++ b/src/datapage.js
@@ -1,12 +1,76 @@
 import { Encoding, PageType } from 'hyparquet/src/constants.js'
+import { ByteWriter } from './bytewriter.js'
 import { writeRleBitPackedHybrid } from './encoding.js'
+import { writePlain } from './plain.js'
+import { snappyCompress } from './snappy.js'
 import { serializeTCompactProtocol } from './thrift.js'
 import { getMaxDefinitionLevel, getMaxRepetitionLevel } from './schema.js'
 
 /**
- * @import {DecodedArray, PageHeader, SchemaElement} from 'hyparquet'
  * @import {Writer} from '../src/types.js'
  * @param {Writer} writer
+ * @param {DecodedArray} values
+ * @param {ParquetType} type
+ * @param {SchemaElement[]} schemaPath
+ * @param {import('hyparquet').Encoding} encoding
+ * @param {boolean} compressed
+ */
+export function writeDataPageV2(writer, values, type, schemaPath, encoding, compressed) {
+  const num_values = values.length
+
+  // write levels to temp buffer
+  const levels = new ByteWriter()
+  const { definition_levels_byte_length, repetition_levels_byte_length, num_nulls }
+     = writeLevels(levels, schemaPath, values)
+
+  const nonnull = values.filter(v => v !== null && v !== undefined)
+
+  // write page data to temp buffer
+  const page = new ByteWriter()
+  if (encoding === 'RLE_DICTIONARY') {
+    const maxValue = Math.max(...nonnull)
+    const bitWidth = Math.ceil(Math.log2(maxValue + 1))
+    page.appendUint8(bitWidth)
+    writeRleBitPackedHybrid(page, nonnull)
+  } else {
+    writePlain(page, nonnull, type)
+  }
+
+  // compress page data
+  let compressedPage = page
+  if (compressed) {
+    compressedPage = new ByteWriter()
+    snappyCompress(compressedPage, new Uint8Array(page.getBuffer()))
+  }
+
+  // write page header
+  /** @type {PageHeader} */
+  const header = {
+    type: 'DATA_PAGE_V2',
+    uncompressed_page_size: levels.offset + page.offset,
+    compressed_page_size: levels.offset + compressedPage.offset,
+    data_page_header_v2: {
+      num_values,
+      num_nulls,
+      num_rows: num_values,
+      encoding,
+      definition_levels_byte_length,
+      repetition_levels_byte_length,
+      is_compressed: compressed,
+    },
+  }
+  writePageHeader(writer, header)
+
+  // write levels
+  writer.appendBuffer(levels.getBuffer())
+
+  // write page data
+  writer.appendBuffer(compressedPage.getBuffer())
+}
+
+/**
+ * @import {DecodedArray, PageHeader, ParquetType, SchemaElement} from 'hyparquet'
+ * @param {Writer} writer
  * @param {PageHeader} header
  */
 export function writePageHeader(writer, header) {
@@ -46,7 +110,7 @@ export function writePageHeader(writer, header) {
  * @param {DecodedArray} values
  * @returns {{ definition_levels_byte_length: number, repetition_levels_byte_length: number, num_nulls: number}}
  */
-export function writeLevels(writer, schemaPath, values) {
+function writeLevels(writer, schemaPath, values) {
   let num_nulls = 0
 
   // TODO: repetition levels
diff --git a/test/write.buffer.test.js b/test/write.buffer.test.js
index c0e7748..c7b4864 100644
--- a/test/write.buffer.test.js
+++ b/test/write.buffer.test.js
@@ -62,7 +62,7 @@ describe('parquetWriteBuffer', () => {
     const str = 'a'.repeat(10000)
     const columnData = [{ name: 'string', data: [str] }]
     const file = parquetWriteBuffer({ columnData, compressed: false })
-    expect(file.byteLength).toBe(10175)
+    expect(file.byteLength).toBe(10176)
   })
 
   it('efficiently serializes column with few distinct values', async () => {