diff --git a/cli/index.js b/cli/index.js
index 20c8e2b..5f8925b 100644
--- a/cli/index.js
+++ b/cli/index.js
@@ -15,18 +15,20 @@ const summarize = require('./src/utils/summarize')
 
 const run = async () => {
   const results = analyse(markDuplicates(files))
+  const baseBranch = flags.baseBranch || 'main'
 
-  if (ci && branch === 'master' && !process.env.INTERNAL_SKIP_CACHE) {
+  if (ci && branch === baseBranch && !process.env.INTERNAL_SKIP_CACHE) {
     await cache.save(results)
   }
   const cachedResults = await cache.read()
 
-  const summary = summarize(results, cachedResults)
+  const summary = summarize(results, cachedResults, { baseBranch })
   cli.report(summary)
 
   if (ci && flags.enableGitHubChecks) {
     const summaryWithoutColors = summarize(results, cachedResults, {
       colors: false,
+      baseBranch
     })
     await github.report(summaryWithoutColors)
   }
diff --git a/cli/src/pipeline/config.js b/cli/src/pipeline/config.js
index 43d836c..1ad13b2 100644
--- a/cli/src/pipeline/config.js
+++ b/cli/src/pipeline/config.js
@@ -15,6 +15,10 @@ program
     '--enable-github-checks',
     'Enable checks on GitHub (needs installation)'
   )
+  .option(
+    '--base-branch',
+    'Specify which branch to use as a baseline for comparison'
+  )
   .option('-f, --files [files]', '(legacy) files to test against (dist/*.js)')
   .option('-s, --max-size [maxSize]', '(legacy) maximum size threshold (3Kb)')
   .option(
@@ -86,6 +90,7 @@ debug('selected config', files)
 const flags = {
   debug: program.debug,
   enableGitHubChecks: program.enableGithubChecks,
+  baseBranch: program.baseBranch,
 }
 
 module.exports = { files, flags }
diff --git a/cli/src/utils/summarize.js b/cli/src/utils/summarize.js
index dbf91e6..7be43ca 100644
--- a/cli/src/utils/summarize.js
+++ b/cli/src/utils/summarize.js
@@ -6,7 +6,7 @@ const { Colors, WithoutColors } = require('./colors')
 
 const summarize = (results, cachedResults = [], options = {}) => {
   const colors = options.colors === false ? WithoutColors : Colors
-  const baseBranch = options.baseBranch || 'master'
+  const baseBranch = options.baseBranch
 
   const status = results.status
 
diff --git a/next-steps.md b/next-steps.md
index 270a92b..8c394e1 100644
--- a/next-steps.md
+++ b/next-steps.md
@@ -1,7 +1,7 @@
 - [x] make checks opt in
 - [x] improve title message if there's only one file
 - [ ] pass ci build if failed check was added
-- [ ] allow customisation of base branch, make main and master default
+- [x] allow customisation of base branch, make main default
 - [ ] rewrite readme
 - [ ] match fuzzy rules from cache
 - [ ] add cumulative diff with master in title [#22](https://github.com/siddharthkp/bundlesize2/issues/22)