diff --git a/core/lib/Drupal/Component/Gettext/PoStreamReader.php b/core/lib/Drupal/Component/Gettext/PoStreamReader.php
index e3ac4b8..61c6083 100644
--- a/core/lib/Drupal/Component/Gettext/PoStreamReader.php
+++ b/core/lib/Drupal/Component/Gettext/PoStreamReader.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Definition of Drupal\Component\Gettext\PoStreamReader.
+ * Contains \Drupal\Component\Gettext\PoStreamReader.
  */
 
 namespace Drupal\Component\Gettext;
@@ -10,6 +10,7 @@
 use Drupal\Component\Gettext\PoReaderInterface;
 use Drupal\Component\Gettext\PoStreamInterface;
 use Drupal\Component\Gettext\PoHeader;
+use Drupal\Component\Utility\String;
 
 /**
  * Implements Gettext PO stream reader.
@@ -305,7 +306,7 @@ private function readLine() {
         }
         else {
           // A comment following any other context is a syntax error.
-          $this->_errors[] = t('The translation stream %uri contains an error: "msgstr" was expected but not found on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: "msgstr" was expected but not found on line %line.', $log_vars);
           return FALSE;
         }
         return;
@@ -315,7 +316,7 @@ private function readLine() {
 
         if ($this->_context != 'MSGID') {
           // A plural form can only be added to an msgid directly.
-          $this->_errors[] = t('The translation stream %uri contains an error: "msgid_plural" was expected but not found on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: "msgid_plural" was expected but not found on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -326,7 +327,7 @@ private function readLine() {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // The plural form must be wrapped in quotes.
-          $this->_errors[] = t('The translation stream %uri contains a syntax error on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains a syntax error on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -353,7 +354,7 @@ private function readLine() {
         }
         elseif ($this->_context == 'MSGID') {
           // We are currently already in the context, meaning we passed an id with no data.
-          $this->_errors[] = t('The translation stream %uri contains an error: "msgid" is unexpected on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: "msgid" is unexpected on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -364,7 +365,7 @@ private function readLine() {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // The message id must be wrapped in quotes.
-          $this->_errors[] = t('The translation stream %uri contains an error: invalid format for "msgid" on line %line.', $log_vars, $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: invalid format for "msgid" on line %line.', $log_vars, $log_vars);
           return FALSE;
         }
 
@@ -382,7 +383,7 @@ private function readLine() {
         }
         elseif (!empty($this->_current_item['msgctxt'])) {
           // A context cannot apply to another context.
-          $this->_errors[] = t('The translation stream %uri contains an error: "msgctxt" is unexpected on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: "msgctxt" is unexpected on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -393,7 +394,7 @@ private function readLine() {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // The context string must be quoted.
-          $this->_errors[] = t('The translation stream %uri contains an error: invalid format for "msgctxt" on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: invalid format for "msgctxt" on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -411,13 +412,13 @@ private function readLine() {
             ($this->_context != 'MSGSTR_ARR')) {
           // Plural message strings must come after msgid, msgxtxt,
           // msgid_plural, or other msgstr[] entries.
-          $this->_errors[] = t('The translation stream %uri contains an error: "msgstr[]" is unexpected on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: "msgstr[]" is unexpected on line %line.', $log_vars);
           return FALSE;
         }
 
         // Ensure the plurality is terminated.
         if (strpos($line, ']') === FALSE) {
-          $this->_errors[] = t('The translation stream %uri contains an error: invalid format for "msgstr[]" on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: invalid format for "msgstr[]" on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -432,7 +433,7 @@ private function readLine() {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // The string must be quoted.
-          $this->_errors[] = t('The translation stream %uri contains an error: invalid format for "msgstr[]" on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: invalid format for "msgstr[]" on line %line.', $log_vars);
           return FALSE;
         }
         if (!isset($this->_current_item['msgstr']) || !is_array($this->_current_item['msgstr'])) {
@@ -449,7 +450,7 @@ private function readLine() {
 
         if (($this->_context != 'MSGID') && ($this->_context != 'MSGCTXT')) {
           // Strings are only valid within an id or context scope.
-          $this->_errors[] = t('The translation stream %uri contains an error: "msgstr" is unexpected on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: "msgstr" is unexpected on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -460,7 +461,7 @@ private function readLine() {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // The string must be quoted.
-          $this->_errors[] = t('The translation stream %uri contains an error: invalid format for "msgstr" on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: invalid format for "msgstr" on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -475,7 +476,7 @@ private function readLine() {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // This string must be quoted.
-          $this->_errors[] = t('The translation stream %uri contains an error: string continuation expected on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: string continuation expected on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -505,7 +506,7 @@ private function readLine() {
         }
         else {
           // No valid context to append to.
-          $this->_errors[] = t('The translation stream %uri contains an error: unexpected string on line %line.', $log_vars);
+          $this->_errors[] = String::format('The translation stream %uri contains an error: unexpected string on line %line.', $log_vars);
           return FALSE;
         }
         return;
@@ -518,7 +519,7 @@ private function readLine() {
       $this->_current_item = array();
     }
     elseif ($this->_context != 'COMMENT') {
-      $this->_errors[] = t('The translation stream %uri ended unexpectedly at line %line.', $log_vars);
+      $this->_errors[] = String::format('The translation stream %uri ended unexpectedly at line %line.', $log_vars);
       return FALSE;
     }
   }