diff --git a/src/Monolog/Formatter/GoogleCloudLoggingFormatter.php b/src/Monolog/Formatter/GoogleCloudLoggingFormatter.php
index d37d1e0c..ea555d4d 100644
--- a/src/Monolog/Formatter/GoogleCloudLoggingFormatter.php
+++ b/src/Monolog/Formatter/GoogleCloudLoggingFormatter.php
@@ -17,6 +17,7 @@ use Monolog\LogRecord;
 /**
  * Encodes message information into JSON in a format compatible with Cloud logging.
  *
+ * @see https://cloud.google.com/logging/docs/structured-logging
  * @see https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry
  *
  * @author Luís Cobucci <lcobucci@gmail.com>
@@ -29,7 +30,7 @@ final class GoogleCloudLoggingFormatter extends JsonFormatter
 
         // Re-key level for GCP logging
         $normalized['severity'] = $normalized['level_name'];
-        $normalized['timestamp'] = $record->datetime->format(DateTimeInterface::RFC3339_EXTENDED);
+        $normalized['time'] = $record->datetime->format(DateTimeInterface::RFC3339_EXTENDED);
 
         // Remove keys that are not used by GCP
         unset($normalized['level'], $normalized['level_name'], $normalized['datetime']);
diff --git a/tests/Monolog/Formatter/GoogleCloudLoggingFormatterTest.php b/tests/Monolog/Formatter/GoogleCloudLoggingFormatterTest.php
index e46846ae..7888caa7 100644
--- a/tests/Monolog/Formatter/GoogleCloudLoggingFormatterTest.php
+++ b/tests/Monolog/Formatter/GoogleCloudLoggingFormatterTest.php
@@ -30,8 +30,8 @@ class GoogleCloudLoggingFormatterTest extends TestCase
 
         $formatted_decoded = json_decode($formatter->format($record), true);
         $this->assertArrayNotHasKey("datetime", $formatted_decoded);
-        $this->assertArrayHasKey("timestamp", $formatted_decoded);
-        $this->assertSame($record->datetime->format(DateTimeInterface::RFC3339_EXTENDED), $formatted_decoded["timestamp"]);
+        $this->assertArrayHasKey("time", $formatted_decoded);
+        $this->assertSame($record->datetime->format(DateTimeInterface::RFC3339_EXTENDED), $formatted_decoded["time"]);
     }
 
     /**