diff --git a/src/Carbon/CarbonInterval.php b/src/Carbon/CarbonInterval.php
index 3ce70193cc..d465beac70 100644
--- a/src/Carbon/CarbonInterval.php
+++ b/src/Carbon/CarbonInterval.php
@@ -1654,8 +1654,14 @@ public function forHumans($syntax = null, $short = false, $parts = -1, $options
                 \count($intervalValues->getNonZeroValues()) > $parts &&
                 ($count = \count($keys = array_keys($intervalValues->getValuesSequence()))) > 1
             ) {
+                $index = min($count, $previousCount - 1) - 2;
+
+                if ($index < 0) {
+                    break;
+                }
+
                 $intervalValues = $this->copy()->roundUnit(
-                    $keys[min($count, $previousCount - 1) - 2],
+                    $keys[$index],
                     1,
                     $method
                 );
diff --git a/tests/CarbonInterval/ForHumansTest.php b/tests/CarbonInterval/ForHumansTest.php
index 11de23266a..8179f60066 100644
--- a/tests/CarbonInterval/ForHumansTest.php
+++ b/tests/CarbonInterval/ForHumansTest.php
@@ -392,6 +392,19 @@ public function testRoundCarryOverDoesntMatter()
         $this->assertSame('3 months', $interval->forHumans(['parts' => 1, 'options' => CarbonInterface::CEIL]));
     }
 
+    public function testCeilShortMonth()
+    {
+        Carbon::setTestNow('2022-02-08T10:27:03Z');
+        $this->assertSame(
+            '4 weeks ago',
+            Carbon::parse('2022-01-11 15:36:29')->diffForHumans(['parts' => 1, 'options' => Carbon::CEIL])
+        );
+        $this->assertSame(
+            '1 month ago',
+            Carbon::parse('2022-01-10 16:57:38')->diffForHumans(['parts' => 1, 'options' => Carbon::CEIL])
+        );
+    }
+
     public function testSkipUnits()
     {
         CarbonInterval::setLocale('en');