diff --git a/lib/platform/azure/index.ts b/lib/platform/azure/index.ts
index e3648c1f983b7e813b46ca44933cad1b935df8aa..edeedc15f95c0b0d129c3e1407d1f784a209609f 100644
--- a/lib/platform/azure/index.ts
+++ b/lib/platform/azure/index.ts
@@ -182,11 +182,8 @@ export function getRepoForceRebase(): Promise<boolean> {
   return Promise.resolve(config.repoForceRebase === true);
 }
 
-// Search
-
-export /* istanbul ignore next */ async function setBaseBranch(
-  branchName = config.baseBranch
-): Promise<string> {
+// istanbul ignore next
+export async function setBaseBranch(branchName: string): Promise<string> {
   logger.debug(`Setting baseBranch to ${branchName}`);
   config.baseBranch = branchName;
   delete config.baseCommitSHA;
diff --git a/lib/platform/bitbucket-server/index.spec.ts b/lib/platform/bitbucket-server/index.spec.ts
index 69452e1ec5421465d1ac32cb123f8b7aada025aa..d2af78c6b4e1e9464817b6c9084eb0cf488a5188 100644
--- a/lib/platform/bitbucket-server/index.spec.ts
+++ b/lib/platform/bitbucket-server/index.spec.ts
@@ -396,7 +396,6 @@ describe(getName(__filename), () => {
           expect.assertions(1);
           await initRepo();
           await bitbucket.setBaseBranch('branch');
-          await bitbucket.setBaseBranch();
           expect(httpMock.getTrace()).toMatchSnapshot();
         });
       });
diff --git a/lib/platform/bitbucket-server/index.ts b/lib/platform/bitbucket-server/index.ts
index 3b11ef91dae02686b37dc89d73f0f647655d4ff9..21242e32bb46831a0424d2ca611a8defb0261155 100644
--- a/lib/platform/bitbucket-server/index.ts
+++ b/lib/platform/bitbucket-server/index.ts
@@ -239,9 +239,7 @@ export async function getRepoForceRebase(): Promise<boolean> {
   );
 }
 
-export async function setBaseBranch(
-  branchName: string = config.defaultBranch
-): Promise<string> {
+export async function setBaseBranch(branchName: string): Promise<string> {
   config.baseBranch = branchName;
   const baseBranchSha = await git.setBranch(branchName);
   return baseBranchSha;
diff --git a/lib/platform/bitbucket/index.spec.ts b/lib/platform/bitbucket/index.spec.ts
index 6e44674dc37ce7d96b77400c7b691652f080a08d..c13f29300e21a196957555c26a2137e4978576e4 100644
--- a/lib/platform/bitbucket/index.spec.ts
+++ b/lib/platform/bitbucket/index.spec.ts
@@ -189,7 +189,6 @@ describe('platform/bitbucket', () => {
     it('updates file list', async () => {
       await initRepoMock();
       await bitbucket.setBaseBranch('branch');
-      await bitbucket.setBaseBranch();
       expect(httpMock.getTrace()).toMatchSnapshot();
     });
   });
diff --git a/lib/platform/bitbucket/index.ts b/lib/platform/bitbucket/index.ts
index 28c5d8215bdb30bf6ccb892b6cf3b95fe75af782..cfd1f782d9e777c2b2803a351720610afb042edb 100644
--- a/lib/platform/bitbucket/index.ts
+++ b/lib/platform/bitbucket/index.ts
@@ -175,11 +175,7 @@ export function getRepoForceRebase(): Promise<boolean> {
   return Promise.resolve(false);
 }
 
-// Search
-
-export async function setBaseBranch(
-  branchName = config.baseBranch
-): Promise<string> {
+export async function setBaseBranch(branchName: string): Promise<string> {
   logger.debug(`Setting baseBranch to ${branchName}`);
   config.baseBranch = branchName;
   delete config.baseCommitSHA;
diff --git a/lib/platform/common.ts b/lib/platform/common.ts
index a5fccf2168505ecfce425caac5c70abda0a85fbd..cc556f694c7b9f1933e23efccbde184a1b6d4848 100644
--- a/lib/platform/common.ts
+++ b/lib/platform/common.ts
@@ -154,7 +154,7 @@ export interface Platform {
   ): Promise<void>;
   deleteBranch(branchName: string, closePr?: boolean): Promise<void>;
   ensureComment(ensureComment: EnsureCommentConfig): Promise<boolean>;
-  setBaseBranch(baseBranch?: string): Promise<string>;
+  setBaseBranch(branchName: string): Promise<string>;
   getPr(number: number): Promise<Pr>;
   findPr(findPRConfig: FindPRConfig): Promise<Pr>;
   refreshPr?(number: number): Promise<void>;
diff --git a/lib/platform/gitea/index.spec.ts b/lib/platform/gitea/index.spec.ts
index e075a87fb2af19c04da2183d435eb8fb64a52a5c..43211bfa2654ca65b9e82a8c0aa7650ae207b72f 100644
--- a/lib/platform/gitea/index.spec.ts
+++ b/lib/platform/gitea/index.spec.ts
@@ -386,9 +386,9 @@ describe('platform/gitea', () => {
       expect(logger.warn).toHaveBeenCalledTimes(1);
     });
 
-    it('should set default base branch', async () => {
+    it('should set base branch', async () => {
       await initFakeRepo();
-      await gitea.setBaseBranch();
+      await gitea.setBaseBranch('master');
 
       expect(gitvcs.setBranch).toHaveBeenCalledTimes(1);
       expect(gitvcs.setBranch).toHaveBeenCalledWith(mockRepo.default_branch);
diff --git a/lib/platform/gitea/index.ts b/lib/platform/gitea/index.ts
index 919776efff684e825dd92141ae2541a1f2747056..76b5c5da981fbccf10a91a77955bd7fd0240c26c 100644
--- a/lib/platform/gitea/index.ts
+++ b/lib/platform/gitea/index.ts
@@ -447,9 +447,7 @@ const platform: Platform = {
     return BranchStatus.yellow;
   },
 
-  async setBaseBranch(
-    baseBranch: string = config.defaultBranch
-  ): Promise<string> {
+  async setBaseBranch(baseBranch: string): Promise<string> {
     config.baseBranch = baseBranch;
     const baseBranchSha = await git.setBranch(baseBranch);
     return baseBranchSha;
diff --git a/lib/platform/github/index.ts b/lib/platform/github/index.ts
index 47df331dbd961427ff4919b29bec8049a78712ab..4d47be3981f0ebc1e225d4d5403f9e2ec4409ae9 100644
--- a/lib/platform/github/index.ts
+++ b/lib/platform/github/index.ts
@@ -500,9 +500,7 @@ export async function getRepoForceRebase(): Promise<boolean> {
 }
 
 // istanbul ignore next
-export async function setBaseBranch(
-  branchName = config.baseBranch
-): Promise<string> {
+export async function setBaseBranch(branchName: string): Promise<string> {
   config.baseBranch = branchName;
   config.baseCommitSHA = null;
   const baseBranchSha = await git.setBranch(branchName);
diff --git a/lib/platform/gitlab/__snapshots__/index.spec.ts.snap b/lib/platform/gitlab/__snapshots__/index.spec.ts.snap
index 2ece084bd0707369c646f00454f97300bc05af7e..0de65bebf73f4929863acbf26606e7427d22e963 100644
--- a/lib/platform/gitlab/__snapshots__/index.spec.ts.snap
+++ b/lib/platform/gitlab/__snapshots__/index.spec.ts.snap
@@ -1690,22 +1690,6 @@ Array [
 ]
 `;
 
-exports[`platform/gitlab setBaseBranch(branchName) uses default base branch 1`] = `
-Array [
-  Object {
-    "headers": Object {
-      "accept": "application/json",
-      "accept-encoding": "gzip, deflate",
-      "host": "gitlab.com",
-      "private-token": "abc123",
-      "user-agent": "https://github.com/renovatebot/renovate",
-    },
-    "method": "GET",
-    "url": "https://gitlab.com/api/v4/projects/some%2Frepo",
-  },
-]
-`;
-
 exports[`platform/gitlab setBranchStatus sets branch status green 1`] = `
 Array [
   Object {
diff --git a/lib/platform/gitlab/index.spec.ts b/lib/platform/gitlab/index.spec.ts
index 444bee0e929e6269ac3e1f9a3a49807a0e48d209..bacbb9eace113a6f3dd1ced3de8978a64d4ed91a 100644
--- a/lib/platform/gitlab/index.spec.ts
+++ b/lib/platform/gitlab/index.spec.ts
@@ -347,23 +347,7 @@ describe('platform/gitlab', () => {
         localDir: '',
         optimizeForDisabled: false,
       });
-      await gitlab.setBaseBranch();
-      expect(httpMock.getTrace()).toMatchSnapshot();
-    });
-    it('uses default base branch', async () => {
-      httpMock
-        .scope(gitlabApiHost)
-        .get(`/api/v4/projects/some%2Frepo`)
-        .reply(200, {
-          default_branch: 'master',
-          http_url_to_repo: `https://gitlab.com/some/repo.git`,
-        });
-      await gitlab.initRepo({
-        repository: 'some/repo',
-        localDir: '',
-        optimizeForDisabled: false,
-      });
-      await gitlab.setBaseBranch();
+      await gitlab.setBaseBranch('master');
       expect(httpMock.getTrace()).toMatchSnapshot();
     });
   });
diff --git a/lib/platform/gitlab/index.ts b/lib/platform/gitlab/index.ts
index b0ee49e0f5d02f5c3ce6af07391c31cfd710c4e6..1a413b4233ed69ed59c6f72574af88afc5a5bcf0 100644
--- a/lib/platform/gitlab/index.ts
+++ b/lib/platform/gitlab/index.ts
@@ -265,9 +265,7 @@ export function getRepoForceRebase(): Promise<boolean> {
   return Promise.resolve(config?.mergeMethod !== 'merge');
 }
 
-export async function setBaseBranch(
-  branchName = config.baseBranch
-): Promise<string> {
+export async function setBaseBranch(branchName: string): Promise<string> {
   logger.debug(`Setting baseBranch to ${branchName}`);
   config.baseBranch = branchName;
   const baseBranchSha = await git.setBranch(branchName);