diff --git a/CHANGELOG.md b/CHANGELOG.md
index a064e6b..c1fac5f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## v2.9.2
+- [Fix fetching git history](https://github.com/dorny/paths-filter/pull/75)
+
 ## v2.9.1
 - [Fix fetching git history + fallback to unshallow repo](https://github.com/dorny/paths-filter/pull/74)
 
diff --git a/dist/index.js b/dist/index.js
index 71893ad..e79004f 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -3865,36 +3865,33 @@ async function getChangesOnHead() {
     return parseGitDiffOutput(output);
 }
 exports.getChangesOnHead = getChangesOnHead;
-async function getChangesSinceMergeBase(baseRef, ref, initialFetchDepth) {
+async function getChangesSinceMergeBase(base, ref, initialFetchDepth) {
+    const baseRef = `remotes/origin/${base}`;
     async function hasMergeBase() {
         return (await exec_1.default('git', ['merge-base', baseRef, ref], { ignoreReturnCode: true })).code === 0;
     }
     let noMergeBase = false;
     core.startGroup(`Searching for merge-base ${baseRef}...${ref}`);
     try {
-        let init = true;
-        let lastCommitCount = await getCommitCount();
-        let depth = Math.max(lastCommitCount * 2, initialFetchDepth);
-        while (!(await hasMergeBase())) {
-            if (init) {
-                await exec_1.default('git', ['fetch', `--depth=${depth}`, 'origin', `${baseRef}:${baseRef}`, `${ref}`]);
-                init = false;
-            }
-            else {
-                await exec_1.default('git', ['fetch', `--deepen=${depth}`, 'origin', baseRef, ref]);
-            }
-            const commitCount = await getCommitCount();
-            if (commitCount === lastCommitCount) {
-                core.info('No more commits were fetched');
-                core.info('Last attempt will be to fetch full history');
-                await exec_1.default('git', ['fetch', '--unshallow']);
-                if (!(await hasMergeBase())) {
-                    noMergeBase = true;
+        if (!(await hasMergeBase())) {
+            await exec_1.default('git', ['fetch', `--depth=${initialFetchDepth}`, 'origin', base, ref]);
+            let depth = initialFetchDepth;
+            let lastCommitCount = await getCommitCount();
+            while (!(await hasMergeBase())) {
+                depth = Math.min(depth * 2, Number.MAX_SAFE_INTEGER);
+                await exec_1.default('git', ['fetch', `--deepen=${depth}`, 'origin', base, ref]);
+                const commitCount = await getCommitCount();
+                if (commitCount === lastCommitCount) {
+                    core.info('No more commits were fetched');
+                    core.info('Last attempt will be to fetch full history');
+                    await exec_1.default('git', ['fetch']);
+                    if (!(await hasMergeBase())) {
+                        noMergeBase = true;
+                    }
+                    break;
                 }
-                break;
+                lastCommitCount = commitCount;
             }
-            depth = Math.min(depth * 2, Number.MAX_SAFE_INTEGER);
-            lastCommitCount = commitCount;
         }
     }
     finally {
diff --git a/src/git.ts b/src/git.ts
index a55faa6..531c301 100644
--- a/src/git.ts
+++ b/src/git.ts
@@ -54,11 +54,9 @@ export async function getChangesOnHead(): Promise<File[]> {
   return parseGitDiffOutput(output)
 }
 
-export async function getChangesSinceMergeBase(
-  baseRef: string,
-  ref: string,
-  initialFetchDepth: number
-): Promise<File[]> {
+export async function getChangesSinceMergeBase(base: string, ref: string, initialFetchDepth: number): Promise<File[]> {
+  const baseRef = `remotes/origin/${base}`
+
   async function hasMergeBase(): Promise<boolean> {
     return (await exec('git', ['merge-base', baseRef, ref], {ignoreReturnCode: true})).code === 0
   }
@@ -66,28 +64,25 @@ export async function getChangesSinceMergeBase(
   let noMergeBase = false
   core.startGroup(`Searching for merge-base ${baseRef}...${ref}`)
   try {
-    let init = true
-    let lastCommitCount = await getCommitCount()
-    let depth = Math.max(lastCommitCount * 2, initialFetchDepth)
-    while (!(await hasMergeBase())) {
-      if (init) {
-        await exec('git', ['fetch', `--depth=${depth}`, 'origin', `${baseRef}:${baseRef}`, `${ref}`])
-        init = false
-      } else {
-        await exec('git', ['fetch', `--deepen=${depth}`, 'origin', baseRef, ref])
-      }
-      const commitCount = await getCommitCount()
-      if (commitCount === lastCommitCount) {
-        core.info('No more commits were fetched')
-        core.info('Last attempt will be to fetch full history')
-        await exec('git', ['fetch', '--unshallow'])
-        if (!(await hasMergeBase())) {
-          noMergeBase = true
+    if (!(await hasMergeBase())) {
+      await exec('git', ['fetch', `--depth=${initialFetchDepth}`, 'origin', base, ref])
+      let depth = initialFetchDepth
+      let lastCommitCount = await getCommitCount()
+      while (!(await hasMergeBase())) {
+        depth = Math.min(depth * 2, Number.MAX_SAFE_INTEGER)
+        await exec('git', ['fetch', `--deepen=${depth}`, 'origin', base, ref])
+        const commitCount = await getCommitCount()
+        if (commitCount === lastCommitCount) {
+          core.info('No more commits were fetched')
+          core.info('Last attempt will be to fetch full history')
+          await exec('git', ['fetch'])
+          if (!(await hasMergeBase())) {
+            noMergeBase = true
+          }
+          break
         }
-        break
+        lastCommitCount = commitCount
       }
-      depth = Math.min(depth * 2, Number.MAX_SAFE_INTEGER)
-      lastCommitCount = commitCount
     }
   } finally {
     core.endGroup()