diff --git a/packages/pg-protocol/package.json b/packages/pg-protocol/package.json
index 05f74ae10..c3595e853 100644
--- a/packages/pg-protocol/package.json
+++ b/packages/pg-protocol/package.json
@@ -17,7 +17,7 @@
   },
   "scripts": {
     "test": "mocha dist/**/*.test.js",
-    "build": "tsc",
+    "build": "tsc && node script/remove-public-const-enum.js",
     "build:watch": "tsc --watch",
     "prepublish": "yarn build",
     "pretest": "yarn build"
diff --git a/packages/pg-protocol/script/remove-public-const-enum.js b/packages/pg-protocol/script/remove-public-const-enum.js
new file mode 100644
index 000000000..d8536df90
--- /dev/null
+++ b/packages/pg-protocol/script/remove-public-const-enum.js
@@ -0,0 +1,120 @@
+// This task would be better served by recast or something like that.
+// https://github.com/travellocal/babel-plugin-declare-const-enum is a good starting point for that.
+
+const fs = require('fs')
+const path = require('path')
+
+const PATCH_SOURCE = process.argv.slice(2).indexOf('--src') >= 0
+const filepath = path.join(__dirname, PATCH_SOURCE ? '../src/messages.ts' : '../dist/messages.d.ts')
+const backuppath = path.join(
+  __dirname,
+  PATCH_SOURCE ? '../src/messages.const-enum.ts' : '../dist/messages.const-enum.d.ts'
+)
+const otherfiles = ['../src/parser.ts']
+/** @type {string} */
+let srcpath
+if (PATCH_SOURCE) {
+  srcpath = filepath
+} else {
+  // use the filepath if it's newer
+  try {
+    const backupStat = fs.statSync(backuppath)
+    const fileStat = fs.statSync(filepath)
+    srcpath = fileStat.mtimeMs > backupStat.mtimeMs ? filepath : backuppath
+  } catch (err) {
+    if (err.code !== 'ENOENT') {
+      throw err
+    }
+    srcpath = filepath
+  }
+}
+const src = fs.readFileSync(srcpath, 'utf8')
+
+/** @type {({startIndex: number, endIndex: number, content: string})[]} */
+let replacements = []
+
+// find the const enum declarations
+const startRe = PATCH_SOURCE
+  ? /(^|\n)export const enum ([A-Za-z][A-Za-z0-9]+) \{\n*/g
+  : /(^|\n)export declare const enum ([A-Za-z][A-Za-z0-9]+) \{\n*/g
+const endRe = /\n\}/g
+
+const constEnums = {}
+
+/** @type {RegExpExecArray | null} */
+let match
+while ((match = startRe.exec(src))) {
+  const startIndex = match.index
+  const name = match[2]
+  const contentStartIndex = (endRe.lastIndex = startRe.lastIndex)
+  const end = endRe.exec(src)
+  if (!end) break
+  const contentEndIndex = end.index
+  const endIndex = (startRe.lastIndex = endRe.lastIndex)
+
+  // collect the members of the const enum
+  const constEnumContent = src.slice(contentStartIndex, contentEndIndex)
+  const itemRe = /\b([A-Za-z][A-Za-z0-9]+)\s*=\s*(.+),/g
+  const lastRe = /\b([A-Za-z][A-Za-z0-9]+)\s*=\s*(.+)/g
+
+  const enumItems = (constEnums[name] = {})
+  const enumValueLiterals = []
+
+  /** @type {RegExpExecArray | null} */
+  let itemMatch
+  while ((itemMatch = itemRe.exec(constEnumContent))) {
+    enumValueLiterals.push((enumItems[itemMatch[1]] = itemMatch[2]))
+    lastRe.lastIndex = itemRe.lastIndex
+  }
+  itemMatch = lastRe.exec(constEnumContent)
+  if (itemMatch) {
+    enumValueLiterals.push((enumItems[itemMatch[1]] = itemMatch[2]))
+  }
+
+  replacements.push({
+    startIndex,
+    endIndex,
+    content: `${match[1]}export type ${name} =\n${enumValueLiterals.map((s) => `    | ${s}`).join('\n')};`,
+  })
+}
+
+if (replacements.length > 0) {
+  // replace the const enum declarations with a literal type union
+  let out = replacements
+    .sort((a, b) => a.startIndex - b.startIndex)
+    .reduce((out, { endIndex, content }, i, r) => {
+      const next = r[i + 1]
+      return out + content + src.slice(endIndex, next && next.startIndex)
+    }, src.slice(0, replacements[0].startIndex))
+
+  // replace references to the enum with the literals
+  for (const enumName of Object.keys(constEnums)) {
+    const enumItems = constEnums[enumName]
+    const re = new RegExp(`\\b${enumName}\\.(${Object.keys(enumItems).join('|')})\\b`, 'g')
+
+    out = out.replace(re, (s, enumItemName) => enumItems[enumItemName])
+  }
+
+  if (!PATCH_SOURCE && srcpath === filepath) {
+    fs.writeFileSync(backuppath, src, 'utf8')
+  }
+  fs.writeFileSync(filepath, out, 'utf8')
+  if (!PATCH_SOURCE) {
+    const now = new Date()
+    fs.utimesSync(backuppath, now, now)
+  } else {
+    for (const f of otherfiles) {
+      const otherfile = path.join(__dirname, f)
+
+      let otherOut = fs.readFileSync(otherfile, 'utf8')
+      // replace references to the enum with the literals
+      for (const enumName of Object.keys(constEnums)) {
+        const enumItems = constEnums[enumName]
+        const re = new RegExp(`\\b${enumName}\\.(${Object.keys(enumItems).join('|')})\\b`, 'g')
+
+        otherOut = otherOut.replace(re, (s, enumItemName) => enumItems[enumItemName])
+      }
+      fs.writeFileSync(otherfile, otherOut, 'utf8')
+    }
+  }
+}