diff --git a/src/components/SideBar.tsx b/src/components/SideBar.tsx
index 2e70fda..50b3649 100644
--- a/src/components/SideBar.tsx
+++ b/src/components/SideBar.tsx
@@ -52,7 +52,12 @@ const RawGitako: React.FC<Props & ConnectorState> = function RawGitako(props) {
    * Catch unexpected PJAX, force trigger init on scope change.
    */
   const pageScope = useStateIO(platform.resolvePageScope?.())
-  useOnPJAXDone(() => pageScope.onChange(platform.resolvePageScope?.()))
+  useOnPJAXDone(
+    React.useCallback(
+      () => pageScope.onChange(platform.resolvePageScope?.(metaData?.defaultBranchName)),
+      [metaData?.defaultBranchName],
+    ),
+  )
   React.useEffect(() => {
     props.init()
   }, [accessToken, pageScope.value])
diff --git a/src/driver/core/SideBar.ts b/src/driver/core/SideBar.ts
index 43b5c6d..31d21f8 100644
--- a/src/driver/core/SideBar.ts
+++ b/src/driver/core/SideBar.ts
@@ -43,7 +43,7 @@ export const init: BoundMethodCreator = dispatch => async () => {
       dispatch.set({ state: 'disabled' })
       return
     }
-    const { userName, repoName, branchName } = metaData
+    const { userName, repoName, branchName, defaultBranchName } = metaData
 
     DOMHelper.markGitakoReadyState(true)
     dispatch.set({
@@ -70,10 +70,11 @@ export const init: BoundMethodCreator = dispatch => async () => {
     getTreeData.catch(error => error) // catch it early to prevent the error being raised higher
 
     if (branchName) {
-      const safeMetaData = {
+      const safeMetaData: MetaData = {
         userName,
         repoName,
         branchName,
+        defaultBranchName,
       }
       dispatch.set({ metaData: safeMetaData })
       getTreeData.catch(error => {
@@ -89,10 +90,11 @@ export const init: BoundMethodCreator = dispatch => async () => {
         throw new Error(`Failed resolving default branch name`)
       }
 
-      const safeMetaData = {
+      const safeMetaData: MetaData = {
         userName,
         repoName,
         branchName: defaultBranchName,
+        defaultBranchName,
       }
       dispatch.set({ metaData: safeMetaData })
 
diff --git a/src/global.d.ts b/src/global.d.ts
index a7771b6..081c987 100644
--- a/src/global.d.ts
+++ b/src/global.d.ts
@@ -2,6 +2,7 @@ type MetaData = {
   userName: string
   repoName: string
   branchName: string
+  defaultBranchName?: string
   type?: EnumString<'tree' | 'blob' | 'pull'>
 }
 
diff --git a/src/platforms/GitHub/DOMHelper.ts b/src/platforms/GitHub/DOMHelper.ts
index 146812a..0d62f0e 100644
--- a/src/platforms/GitHub/DOMHelper.ts
+++ b/src/platforms/GitHub/DOMHelper.ts
@@ -232,3 +232,23 @@ export function attachCopySnippet() {
     )
   })
 }
+
+export function getPath() {
+  const folderPathElementSelector = '.file-navigation .position-relative' // available when in path like '/tree/...'
+  const blobPathElementSelector = '#blob-path' // available when in path like '/blob/...'
+  const pathElement =
+    document.querySelector(blobPathElementSelector) ||
+    document.querySelector(folderPathElementSelector)?.nextElementSibling
+  if (!pathElement || !pathElement.querySelector('.js-repo-root')) {
+    raiseError(new Error(`Path element not found`))
+    return ''
+  }
+  const path = ((pathElement as HTMLDivElement).innerText || '')
+    .replace(/ \/ Jump to $/, '')
+    .trim()
+    .split('/')
+    .filter(Boolean)
+    .slice(1) // the first is the repo's name
+    .join('/')
+  return path
+}
diff --git a/src/platforms/GitHub/index.ts b/src/platforms/GitHub/index.ts
index 49cf7c0..4b63d68 100644
--- a/src/platforms/GitHub/index.ts
+++ b/src/platforms/GitHub/index.ts
@@ -1,3 +1,4 @@
+import { raiseError } from 'analytics'
 import { GITHUB_OAUTH } from 'env'
 import { Base64 } from 'js-base64'
 import { platform } from 'platforms'
@@ -82,6 +83,40 @@ export function isEnterprise() {
   return !window.location.host.endsWith('github.com')
 }
 
+function getBranchName() {
+  const pathFromDOM = DOMHelper.getPath()
+  const pathAndBranchFromURL = URLHelper.parse().path.filter(Boolean).join('/')
+  if (pathAndBranchFromURL.endsWith(pathFromDOM)) {
+    return pathAndBranchFromURL
+      .slice(0, pathAndBranchFromURL.length - pathFromDOM.length)
+      .replace(/\/$/, '')
+  }
+  raiseError(new Error(`Parsed path not end with path from DOM`))
+}
+
+function resolvePageScope(defaultBranchName?: string) {
+  const parsed = URLHelper.parse()
+  switch (parsed.type) {
+    // case undefined:
+    //   return `branch-${defaultBranchName}`
+    case 'blob':
+    case 'tree': {
+      // handle URLs like {user}/{repo}/tree/{sha|branch}, issue#131
+      const branchName = getBranchName()
+      if (branchName && branchName !== defaultBranchName) return `branch-${branchName}`
+      break
+    }
+    case 'tags':
+      return 'tags'
+    case 'releases':
+      return 'releases'
+    case 'pull':
+      const pullId = URLHelper.isInPullPage()
+      if (pullId) return `pull-${pullId}`
+  }
+  return 'general'
+}
+
 const pathSHAMap = new Map<string, string>()
 
 export const GitHub: Platform = {
@@ -115,15 +150,11 @@ export const GitHub: Platform = {
       repoName,
       type,
       branchName,
+      defaultBranchName: type ? undefined : branchName,
     }
     return metaData
   },
-  resolvePageScope() {
-    if (URLHelper.parse().type === 'releases') return 'releases'
-    const pullId = URLHelper.isInPullPage()
-    if (pullId) return `pull-${pullId}`
-    return 'general'
-  },
+  resolvePageScope,
   async getDefaultBranchName({ userName, repoName }, accessToken) {
     const data = await API.getRepoMeta(userName, repoName, accessToken)
     return data.default_branch
diff --git a/src/platforms/platform.d.ts b/src/platforms/platform.d.ts
index 12cd2a6..6bf87ac 100644
--- a/src/platforms/platform.d.ts
+++ b/src/platforms/platform.d.ts
@@ -2,7 +2,7 @@ type Platform = {
   isEnterprise(): boolean
   // branch name might not be available when resolving from DOM and URL
   resolveMeta(): MakeOptional<MetaData, 'branchName'> | null
-  resolvePageScope?(): string
+  resolvePageScope?(branchName?: string): string
   getDefaultBranchName(
     metaData: Pick<MetaData, 'userName' | 'repoName'>,
     accessToken?: string,