diff --git a/lib/util/git/index.ts b/lib/util/git/index.ts
index 8207b3e39853a91f2045ea6d2bf392e1e7acba66..dd64de1abe2c0e355f32b2b82aaf410549e70d1f 100644
--- a/lib/util/git/index.ts
+++ b/lib/util/git/index.ts
@@ -30,6 +30,8 @@ export type StatusResult = StatusResult_;
 
 export type DiffResult = DiffResult_;
 
+export type CommitSha = string;
+
 interface StorageConfig {
   localDir: string;
   currentBranch?: string;
@@ -322,7 +324,7 @@ export async function branchExists(branchName: string): Promise<boolean> {
 }
 
 // Return the commit SHA for a branch
-export async function getBranchCommit(branchName: string): Promise<string> {
+export async function getBranchCommit(branchName: string): Promise<CommitSha> {
   await syncGit();
   if (!(await branchExists(branchName))) {
     throw Error(
@@ -343,7 +345,7 @@ export async function getCommitMessages(): Promise<string[]> {
   return res.all.map((commit) => commit.message);
 }
 
-export async function setBranch(branchName: string): Promise<string> {
+export async function setBranch(branchName: string): Promise<CommitSha> {
   await syncGit();
   if (!(await branchExists(branchName))) {
     throwBranchValidationError(branchName);
@@ -569,7 +571,7 @@ export async function commitFiles({
   files,
   message,
   force = false,
-}: CommitFilesConfig): Promise<string | null> {
+}: CommitFilesConfig): Promise<CommitSha | null> {
   await syncGit();
   logger.debug(`Committing files to branch ${branchName}`);
   if (!privateKeySet) {