diff --git a/lib/git.js b/lib/git.js
index ad6b4b30..474af2ee 100644
--- a/lib/git.js
+++ b/lib/git.js
@@ -36,9 +36,15 @@ async function gitTags() {
  */
 async function isRefInHistory(ref) {
   try {
-    return (await execa('git', ['merge-base', '--is-ancestor', ref, 'HEAD'])).code === 0;
+    await execa('git', ['merge-base', '--is-ancestor', ref, 'HEAD']);
+    return true;
   } catch (err) {
+    if (err.code === 1) {
+      return false;
+    }
+
     debug(err);
+    throw err;
   }
 }
 
diff --git a/test/git.test.js b/test/git.test.js
index 5ca650f5..849914d0 100644
--- a/test/git.test.js
+++ b/test/git.test.js
@@ -91,6 +91,7 @@ test.serial('Verify if the commit `sha` is in the direct history of the current
 
   t.true(await isRefInHistory(commits[0].hash));
   t.falsy(await isRefInHistory(otherCommits[0].hash));
+  await t.throws(isRefInHistory('non-existant-sha'));
 });
 
 test.serial('Get the commit sha for a given tag or falsy if the tag does not exists', async t => {