diff --git a/README.md b/README.md
index 460bae59..c7a4254d 100644
--- a/README.md
+++ b/README.md
@@ -46,6 +46,7 @@ Automate releases with Conventional Commit Messages.
 | `version-file` | provide a path to a version file to increment (used by ruby releaser) |
 | `fork`          | Should the PR be created from a fork (does not work with `secrets.GITHUB_TOKEN`) |
 | `command`          | release-please command to run, either `github-release`, or `release-pr` (_defaults to running both_) |
+| `default-branch`  | branch to open pull release PR against (detected by default) |
 
 | output | description |
 |:---:|---|
diff --git a/action.yml b/action.yml
index b2240579..05df7a61 100644
--- a/action.yml
+++ b/action.yml
@@ -38,6 +38,9 @@ inputs:
   version-file:
     description: 'provide a path to a version file to increment (used by ruby releaser)'
     required: false
+  default-branch:
+    description: 'branch to open pull release PR against (detected by default)'
+    required: false
 runs:
   using: 'node12'
   main: 'dist/index.js'
diff --git a/index.js b/index.js
index 1d2d7ab9..def804db 100644
--- a/index.js
+++ b/index.js
@@ -16,6 +16,7 @@ async function main () {
   const changelogTypes = core.getInput('changelog-types')
   const command = core.getInput('command') ? core.getInput('command') : undefined
   const versionFile = core.getInput('version-file') ? core.getInput('version-file') : undefined
+  const defaultBranch = core.getInput('default-branch') ? core.getInput('default-branch') : undefined
 
   // Parse the changelogTypes if there are any
   let changelogSections
@@ -60,7 +61,8 @@ async function main () {
       label: RELEASE_LABEL,
       bumpMinorPreMajor,
       changelogSections,
-      versionFile
+      versionFile,
+      defaultBranch
     })
     const pr = await release.run()
     if (pr) {
diff --git a/test/release-please.js b/test/release-please.js
index 852fe4ee..61bd2e1c 100644
--- a/test/release-please.js
+++ b/test/release-please.js
@@ -5,7 +5,7 @@ const core = require('@actions/core')
 const sinon = require('sinon')
 
 describe('release-please-action', () => {
-  it('both opens PR and tags GitHub releases by default', async () => {
+  it('both opens PR to the default branch and tags GitHub releases by default', async () => {
     const output = {}
     core.setOutput = (name, value) => {
       output[name] = value
@@ -26,17 +26,59 @@ describe('release-please-action', () => {
       return Release
     }
     const releasePR = sinon.stub().returns(25)
+    const buildStatic = sinon.stub().returns({
+      run: releasePR
+    })
     action.getReleasePRFactory = () => {
       return {
-        buildStatic: () => {
-          return {
-            run: releasePR
-          }
-        }
+        buildStatic
+      }
+    }
+    await action.main()
+    sinon.assert.calledOnce(createRelease)
+    sinon.assert.calledWith(buildStatic, 'node', sinon.match.hasOwn('defaultBranch', undefined))
+    sinon.assert.calledOnce(releasePR)
+    assert.deepStrictEqual(output, {
+      release_created: true,
+      upload_url: 'http://example.com',
+      tag_name: 'v1.0.0',
+      pr: 25
+    })
+  })
+
+  it('both opens PR to a different default branch and tags GitHub releases by default', async () => {
+    const output = {}
+    core.setOutput = (name, value) => {
+      output[name] = value
+    }
+    const input = {
+      'release-type': 'node',
+      'default-branch': 'dev'
+    }
+    core.getInput = (name) => {
+      return input[name]
+    }
+    const createRelease = sinon.stub().returns({
+      upload_url: 'http://example.com',
+      tag_name: 'v1.0.0'
+    })
+    action.getGitHubRelease = () => {
+      class Release {}
+      Release.prototype.createRelease = createRelease
+      return Release
+    }
+    const releasePR = sinon.stub().returns(25)
+    const buildStatic = sinon.stub().returns({
+      run: releasePR
+    })
+    action.getReleasePRFactory = () => {
+      return {
+        buildStatic
       }
     }
     await action.main()
     sinon.assert.calledOnce(createRelease)
+    sinon.assert.calledWith(buildStatic, 'node', sinon.match.hasOwn('defaultBranch', 'dev'))
     sinon.assert.calledOnce(releasePR)
     assert.deepStrictEqual(output, {
       release_created: true,