diff --git a/src/Carbon/Traits/Options.php b/src/Carbon/Traits/Options.php
index 48f9739773..2b0fc23593 100644
--- a/src/Carbon/Traits/Options.php
+++ b/src/Carbon/Traits/Options.php
@@ -80,9 +80,9 @@ trait Options
         'n' => '(1[012]|[1-9])',
         't' => '(2[89]|3[01])',
         'L' => '(0|1)',
-        'o' => '([1-9][0-9]{0,4})',
-        'Y' => '([1-9]?[0-9]{4})',
-        'y' => '([0-9]{2})',
+        'o' => '([0-9]{1,4})',
+        'Y' => '([0-9]{1,4})',
+        'y' => '([0-9]{1,2})',
         'a' => '(am|pm)',
         'A' => '(AM|PM)',
         'B' => '([0-9]{3})',