diff --git a/pre_commit/commands/hook_impl.py b/pre_commit/commands/hook_impl.py
index 0c72d8d5..ddfac519 100644
--- a/pre_commit/commands/hook_impl.py
+++ b/pre_commit/commands/hook_impl.py
@@ -111,7 +111,7 @@ def _ns(
 
 
 def _rev_exists(rev: str) -> bool:
-    return subprocess.call(('git', 'cat-file', '-e', rev))
+    return subprocess.call(('git', 'cat-file', '-e', rev)) == 0
 
 
 def _pre_push_ns(