diff --git a/core/lib/Drupal/Component/Gettext/PoStreamReader.php b/core/lib/Drupal/Component/Gettext/PoStreamReader.php
index d138791..c30311f 100644
--- a/core/lib/Drupal/Component/Gettext/PoStreamReader.php
+++ b/core/lib/Drupal/Component/Gettext/PoStreamReader.php
@@ -105,6 +105,13 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
   private $_finished;
 
   /**
+   * Array of translated error strings recorded on reading this stream so far.
+   *
+   * @var array
+   */
+  private $_errors;
+
+  /**
    * Implements Drupal\Component\Gettext\PoMetadataInterface::getLangcode().
    */
   public function getLangcode() {
@@ -247,6 +254,13 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
       // Track the line number for error reporting.
       $this->_line_number++;
 
+      // Initialize common values for error logging.
+      $log_vars = array(
+        '%uri' => $this->getURI(),
+        '%line' => $this->_line_number,
+      );
+      $t = get_t();
+
       // Trim away the linefeed. \\n might appear at the end of the string if
       // another line continuing the same string follows. We can remove that.
       $line = trim(strtr($line, array("\\\n" => "")));
@@ -271,7 +285,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
         }
         else {
           // A comment following any other context is a syntax error.
-          $this->log('The translation stream %uri contains an error: "msgstr" was expected but not found on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains an error: "msgstr" was expected but not found on line %line.', $log_vars);
           return FALSE;
         }
         return;
@@ -281,7 +295,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
 
         if ($this->_context != 'MSGID') {
           // A plural form can only be added to an msgid directly.
-          $this->log('The translation stream %uri contains an error: "msgid_plural" was expected but not found on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains an error: "msgid_plural" was expected but not found on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -292,7 +306,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // The plural form must be wrapped in quotes.
-          $this->log('The translation stream %uri contains a syntax error on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains a syntax error on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -319,7 +333,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
         }
         elseif ($this->_context == 'MSGID') {
           // We are currently already in the context, meaning we passed an id with no data.
-          $this->log('The translation stream %uri contains an error: "msgid" is unexpected on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains an error: "msgid" is unexpected on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -330,7 +344,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // The message id must be wrapped in quotes.
-          $this->log('The translation stream %uri contains an error: invalid format for "msgid" on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains an error: invalid format for "msgid" on line %line.', $log_vars, $log_vars);
           return FALSE;
         }
 
@@ -348,7 +362,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
         }
         elseif (!empty($this->_current_item['msgctxt'])) {
           // A context cannot apply to another context.
-          $this->log('The translation stream %uri contains an error: "msgctxt" is unexpected on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains an error: "msgctxt" is unexpected on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -359,7 +373,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // The context string must be quoted.
-          $this->log('The translation stream %uri contains an error: invalid format for "msgctxt" on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains an error: invalid format for "msgctxt" on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -374,13 +388,13 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
         if (($this->_context != 'MSGID') && ($this->_context != 'MSGCTXT') && ($this->_context != 'MSGID_PLURAL') && ($this->_context != 'MSGSTR_ARR')) {
           // Plural message strings must come after msgid, msgxtxt,
           // msgid_plural, or other msgstr[] entries.
-          $this->log('The translation stream %uri contains an error: "msgstr[]" is unexpected on line %line.');
+          $this->_errors[] = $t('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->log('The translation stream %uri contains an error: invalid format for "msgstr[]" on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains an error: invalid format for "msgstr[]" on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -395,7 +409,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // The string must be quoted.
-          $this->log('The translation stream %uri contains an error: invalid format for "msgstr[]" on line %line.');
+          $this->_errors[] = $t('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'])) {
@@ -412,7 +426,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
 
         if (($this->_context != 'MSGID') && ($this->_context != 'MSGCTXT')) {
           // Strings are only valid within an id or context scope.
-          $this->log('The translation stream %uri contains an error: "msgstr" is unexpected on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains an error: "msgstr" is unexpected on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -423,7 +437,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // The string must be quoted.
-          $this->log('The translation stream %uri contains an error: invalid format for "msgstr" on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains an error: invalid format for "msgstr" on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -438,7 +452,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
         $quoted = $this->parseQuoted($line);
         if ($quoted === FALSE) {
           // This string must be quoted.
-          $this->log('The translation stream %uri contains an error: string continuation expected on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains an error: string continuation expected on line %line.', $log_vars);
           return FALSE;
         }
 
@@ -468,7 +482,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
         }
         else {
           // No valid context to append to.
-          $this->log('The translation stream %uri contains an error: unexpected string on line %line.');
+          $this->_errors[] = $t('The translation stream %uri contains an error: unexpected string on line %line.', $log_vars);
           return FALSE;
         }
         return;
@@ -481,27 +495,12 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
       $this->_current_item = array();
     }
     elseif ($this->_context != 'COMMENT') {
-      $this->log('The translation stream %uri ended unexpectedly at line %line.');
+      $this->_errors[] = $t('The translation stream %uri ended unexpectedly at line %line.', $log_vars);
       return FALSE;
     }
   }
 
   /**
-   * Sets an error message if an error occurred during PO stream parsing.
-   *
-   * @param string $message
-   *   The message to be translated.
-   */
-  protected function log($message) {
-    $vars = array(
-      '%uri' => $this->getURI(),
-      '%line' => $this->_line_number,
-    );
-    $t = get_t();
-    $this->errorLog[] = $t($message, $vars);
-  }
-
-  /**
    * Store the parsed values as a PoItem object.
    */
   public function setItemFromArray($value) {
diff --git a/core/lib/Drupal/Component/Gettext/PoStreamWriter.php b/core/lib/Drupal/Component/Gettext/PoStreamWriter.php
index 65df423..d066307 100644
--- a/core/lib/Drupal/Component/Gettext/PoStreamWriter.php
+++ b/core/lib/Drupal/Component/Gettext/PoStreamWriter.php
@@ -10,11 +10,13 @@ namespace Drupal\Component\Gettext;
 use Drupal\Component\Gettext\PoHeader;
 use Drupal\Component\Gettext\PoItem;
 use Drupal\Component\Gettext\PoReaderInterface;
+use Drupal\Component\Gettext\PoWriterInterface;
+use Drupal\Component\Gettext\PoStreamInterface;
 
 /**
  * Defines a Gettext PO stream writer.
  */
-class PoStreamWriter implements PoWriterInterface {
+class PoStreamWriter implements PoWriterInterface, PoStreamInterface {
 
   /**
    * URI of the PO stream that is being written.
@@ -144,10 +146,7 @@ class PoStreamWriter implements PoWriterInterface {
   }
 
   /**
-   * Get the URI of the current stream.
-   *
-   * @return string
-   *   The URI of the current stream.
+   * Implements Drupal\Component\Gettext\PoStreamInterface::getURI().
    *
    * @throws Exception
    *   If the URI is not set.
@@ -160,10 +159,7 @@ class PoStreamWriter implements PoWriterInterface {
   }
 
   /**
-   * Set the URI to be used.
-   *
-   * @param string $uri
-   *   Set the strem URI for writing.
+   * Implements Drupal\Component\Gettext\PoStreamInterface::setURI().
    */
   public function setURI($uri) {
     $this->_uri = $uri;