diff --git a/__test__/create-or-update-branch.int.test.ts b/__test__/create-or-update-branch.int.test.ts
index 0f122541d..e392ad439 100644
--- a/__test__/create-or-update-branch.int.test.ts
+++ b/__test__/create-or-update-branch.int.test.ts
@@ -140,10 +140,22 @@ describe('create-or-update-branch tests', () => {
   })
 
   async function beforeTest(): Promise<void> {
+    await git.fetch(
+      [`${DEFAULT_BRANCH}:${DEFAULT_BRANCH}`],
+      REMOTE_NAME,
+      ['--force', '--update-head-ok'],
+      true
+    )
     await git.checkout(DEFAULT_BRANCH)
   }
 
   async function afterTest(deleteRemote = true): Promise<void> {
+    await git.fetch(
+      [`${DEFAULT_BRANCH}:${DEFAULT_BRANCH}`],
+      REMOTE_NAME,
+      ['--force', '--update-head-ok'],
+      true
+    )
     await git.checkout(DEFAULT_BRANCH)
     try {
       // Get the upstream branch if it exists
@@ -1454,8 +1466,7 @@ describe('create-or-update-branch tests', () => {
     expect(
       await gitLogMatches([
         _commitMessage,
-        ...commits.commitMsgs,
-        INIT_COMMIT_MESSAGE
+        commits.commitMsgs[0] // fetch depth of base is 1
       ])
     ).toBeTruthy()
   })
@@ -1590,7 +1601,9 @@ describe('create-or-update-branch tests', () => {
     expect(await getFileContent(TRACKED_FILE)).toEqual(_changes.tracked)
     expect(await getFileContent(UNTRACKED_FILE)).toEqual(_changes.untracked)
     expect(
-      await gitLogMatches([...commits.commitMsgs, INIT_COMMIT_MESSAGE])
+      await gitLogMatches([
+        commits.commitMsgs[0] // fetch depth of base is 1
+      ])
     ).toBeTruthy()
   })
 
@@ -1668,7 +1681,9 @@ describe('create-or-update-branch tests', () => {
     expect(await getFileContent(TRACKED_FILE)).toEqual(_changes.tracked)
     expect(await getFileContent(UNTRACKED_FILE)).toEqual(_changes.untracked)
     expect(
-      await gitLogMatches([...commits.commitMsgs, INIT_COMMIT_MESSAGE])
+      await gitLogMatches([
+        commits.commitMsgs[0] // fetch depth of base is 1
+      ])
     ).toBeTruthy()
   })
 
@@ -1951,8 +1966,7 @@ describe('create-or-update-branch tests', () => {
       await gitLogMatches([
         _commitMessage,
         ..._commits.commitMsgs,
-        ...commitsOnBase.commitMsgs,
-        INIT_COMMIT_MESSAGE
+        commitsOnBase.commitMsgs[0] // fetch depth of base is 1
       ])
     ).toBeTruthy()
   })
@@ -2147,8 +2161,7 @@ describe('create-or-update-branch tests', () => {
     expect(
       await gitLogMatches([
         _commitMessage,
-        ...commitsOnBase.commitMsgs,
-        INIT_COMMIT_MESSAGE
+        commitsOnBase.commitMsgs[0] // fetch depth of base is 1
       ])
     ).toBeTruthy()
   })
diff --git a/dist/index.js b/dist/index.js
index bca7be4f4..57130a626 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -183,8 +183,13 @@ function createOrUpdateBranch(git, commitMessage, base, branch, branchRemoteName
         // This will also be true if the working base type is a commit
         if (workingBase != base) {
             core.info(`Rebasing commits made to ${workingBaseType} '${workingBase}' on to base branch '${base}'`);
+            const fetchArgs = ['--force'];
+            if (branchRemoteName != 'fork') {
+                // If pushing to a fork we cannot shallow fetch otherwise the 'shallow update not allowed' error occurs
+                fetchArgs.push('--depth=1');
+            }
             // Checkout the actual base
-            yield git.fetch([`${base}:${base}`], baseRemote, ['--force']);
+            yield git.fetch([`${base}:${base}`], baseRemote, fetchArgs);
             yield git.checkout(base);
             // Cherrypick commits from the temporary branch starting from the working base
             const commits = yield git.revList([`${workingBase}..${tempBranch}`, '.'], ['--reverse']);
@@ -197,7 +202,7 @@ function createOrUpdateBranch(git, commitMessage, base, branch, branchRemoteName
             // Reset the temp branch to the working index
             yield git.checkout(tempBranch, 'HEAD');
             // Reset the base
-            yield git.fetch([`${base}:${base}`], baseRemote, ['--force']);
+            yield git.fetch([`${base}:${base}`], baseRemote, fetchArgs);
         }
         // Try to fetch the pull request branch
         if (!(yield tryFetch(git, branchRemoteName, branch))) {
diff --git a/src/create-or-update-branch.ts b/src/create-or-update-branch.ts
index 1c55ea5fc..000dc513d 100644
--- a/src/create-or-update-branch.ts
+++ b/src/create-or-update-branch.ts
@@ -199,8 +199,13 @@ export async function createOrUpdateBranch(
     core.info(
       `Rebasing commits made to ${workingBaseType} '${workingBase}' on to base branch '${base}'`
     )
+    const fetchArgs = ['--force']
+    if (branchRemoteName != 'fork') {
+      // If pushing to a fork we cannot shallow fetch otherwise the 'shallow update not allowed' error occurs
+      fetchArgs.push('--depth=1')
+    }
     // Checkout the actual base
-    await git.fetch([`${base}:${base}`], baseRemote, ['--force'])
+    await git.fetch([`${base}:${base}`], baseRemote, fetchArgs)
     await git.checkout(base)
     // Cherrypick commits from the temporary branch starting from the working base
     const commits = await git.revList(
@@ -219,7 +224,7 @@ export async function createOrUpdateBranch(
     // Reset the temp branch to the working index
     await git.checkout(tempBranch, 'HEAD')
     // Reset the base
-    await git.fetch([`${base}:${base}`], baseRemote, ['--force'])
+    await git.fetch([`${base}:${base}`], baseRemote, fetchArgs)
   }
 
   // Try to fetch the pull request branch