diff --git a/config/config.sample.php b/config/config.sample.php
index 4f018d189da64d2c6bdbeb1845ca93666100e8ce..a9ab67374f85827dfd447a31455b235c74011f62 100644
--- a/config/config.sample.php
+++ b/config/config.sample.php
@@ -716,7 +716,9 @@ $CONFIG = array(
 /**
  * This uses PHP.date formatting; see http://php.net/manual/en/function.date.php
  *
- * Defaults to ``Y-m-d\TH:i:sO`` (ISO8601)
+ * Defaults to ``Y-m-d\TH:i:sP`` (ISO8601 but with colon between hours and
+ * minutes of the timezone) - see \DateTime::ISO8601
+ * (https://secure.php.net/manual/en/class.datetime.php#datetime.constants.iso8601)
  */
 'logdateformat' => 'F d, Y H:i:s',
 
diff --git a/lib/private/Console/TimestampFormatter.php b/lib/private/Console/TimestampFormatter.php
index 5b292439a4c3643a0ef598937a58163973ef9825..d68db95f645b0f856eaef6f757c68baa5d768a66 100644
--- a/lib/private/Console/TimestampFormatter.php
+++ b/lib/private/Console/TimestampFormatter.php
@@ -101,7 +101,7 @@ class TimestampFormatter implements OutputFormatterInterface {
 		$timeZone = $timeZone !== null ? new \DateTimeZone($timeZone) : null;
 
 		$time = new \DateTime('now', $timeZone);
-		$timestampInfo = $time->format($this->config->getSystemValue('logdateformat', 'c'));
+		$timestampInfo = $time->format($this->config->getSystemValue('logdateformat', \DateTime::ISO8601));
 
 		return $timestampInfo . ' ' . $this->formatter->format($message);
 	}
diff --git a/lib/private/Log/File.php b/lib/private/Log/File.php
index 904aa1d93f1febad36bd25690247c55802e1f0ee..d41ab83c804be87eca095a1fbfe1f55cd22cf562 100644
--- a/lib/private/Log/File.php
+++ b/lib/private/Log/File.php
@@ -75,8 +75,8 @@ class File {
 		$config = \OC::$server->getSystemConfig();
 
 		// default to ISO8601
-		$format = $config->getValue('logdateformat', 'c');
-		$logTimeZone = $config->getValue( "logtimezone", 'UTC' );
+		$format = $config->getValue('logdateformat', \DateTime::ISO8601);
+		$logTimeZone = $config->getValue('logtimezone', 'UTC');
 		try {
 			$timezone = new \DateTimeZone($logTimeZone);
 		} catch (\Exception $e) {