diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 6f9dd226d8..487a898e4c 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -15,6 +15,7 @@
             <file phpVersion="5.3.0">tests/phpunit/tests/image/editor.php</file>
             <file phpVersion="5.3.0">tests/phpunit/tests/image/editor_gd.php</file>
             <file phpVersion="5.3.0">tests/phpunit/tests/image/editor_imagick.php</file>
+            <file phpVersion="5.3.0">tests/phpunit/tests/oembed/headers.php</file>
         </testsuite>
     </testsuites>
     <groups>
diff --git a/src/wp-includes/class-wp-oembed-controller.php b/src/wp-includes/class-wp-oembed-controller.php
index 0fc25ba817..2da7f3e5db 100644
--- a/src/wp-includes/class-wp-oembed-controller.php
+++ b/src/wp-includes/class-wp-oembed-controller.php
@@ -88,7 +88,7 @@ final class WP_oEmbed_Controller {
 
 		if ( false === $data ) {
 			status_header( 404 );
-			return __( 'Invalid URL.', 'oembed-api' );
+			return __( 'Invalid URL.' );
 		}
 
 		if ( 'json' === $request['format'] ) {
diff --git a/src/wp-includes/embed-functions.php b/src/wp-includes/embed-functions.php
index ad5bfd711e..9e13c6e539 100644
--- a/src/wp-includes/embed-functions.php
+++ b/src/wp-includes/embed-functions.php
@@ -484,7 +484,7 @@ JS;
 		esc_url( $embed_url ),
 		absint( $width ),
 		absint( $height ),
-		esc_attr__( 'Embedded WordPress Post', 'oembed-api' )
+		esc_attr__( 'Embedded WordPress Post' )
 	);
 
 	/**
@@ -748,11 +748,11 @@ function wp_oembed_excerpt_more( $more_string ) {
 	}
 
 	return sprintf(
-		_x( '&hellip; %s', 'read more link', 'oembed-api' ),
+		_x( '&hellip; %s', 'read more link' ),
 		sprintf(
 			'<a class="wp-embed-more" href="%s" target="_top">%s</a>',
 			get_the_permalink(),
-			__( 'Read more', 'oembed-api' )
+			__( 'Read more' )
 		)
 	);
 }
diff --git a/src/wp-includes/embed-template.php b/src/wp-includes/embed-template.php
index 5cfa8e30d1..7a70b1ddd7 100644
--- a/src/wp-includes/embed-template.php
+++ b/src/wp-includes/embed-template.php
@@ -161,8 +161,7 @@ if ( have_posts() ) :
 									_n(
 										'%s <span class="screen-reader-text">Comment</span>',
 										'%s <span class="screen-reader-text">Comments</span>',
-										get_comments_number(),
-										'oembed-api'
+										get_comments_number()
 									),
 									absint( get_comments_number() )
 								);
@@ -172,7 +171,7 @@ if ( have_posts() ) :
 					<?php endif; ?>
 					<div class="wp-embed-share">
 						<button type="button" class="wp-embed-share-dialog-open"
-						        aria-label="<?php esc_attr_e( 'Open sharing dialog', 'oembed-api' ); ?>">
+						        aria-label="<?php esc_attr_e( 'Open sharing dialog' ); ?>">
 							<span class="dashicons dashicons-share"></span>
 						</button>
 					</div>
@@ -183,29 +182,29 @@ if ( have_posts() ) :
 					<div class="wp-embed-share-dialog-text">
 						<ul class="wp-embed-share-tabs" role="tablist">
 							<li id="wp-embed-share-tab-button-wordpress" class="wp-embed-share-tab-button" role="presentation">
-								<button role="tab" aria-controls="wp-embed-share-tab-wordpress" aria-selected="true" tabindex="0"><?php esc_html_e( 'WordPress Embed', 'oembed-api' ); ?></button>
+								<button role="tab" aria-controls="wp-embed-share-tab-wordpress" aria-selected="true" tabindex="0"><?php esc_html_e( 'WordPress Embed' ); ?></button>
 							</li>
 							<li id="wp-embed-share-tab-button-embed" class="wp-embed-share-tab-button" role="presentation">
-								<button role="tab" aria-controls="wp-embed-share-tab-html" aria-selected="false" tabindex="-1"><?php esc_html_e( 'HTML Embed', 'oembed-api' ); ?></button>
+								<button role="tab" aria-controls="wp-embed-share-tab-html" aria-selected="false" tabindex="-1"><?php esc_html_e( 'HTML Embed' ); ?></button>
 							</li>
 						</ul>
 						<div id="wp-embed-share-tab-wordpress" class="wp-embed-share-tab" role="tabpanel" aria-labelledby="wp-embed-share-tab-button-wordpress" aria-hidden="false">
 							<input type="text" value="<?php the_permalink(); ?>" class="wp-embed-share-input" tabindex="0" readonly/>
 
 							<p class="wp-embed-share-description">
-								<?php _e( 'Copy and paste this URL into your WordPress site to embed', 'oembed-api' ); ?>
+								<?php _e( 'Copy and paste this URL into your WordPress site to embed' ); ?>
 							</p>
 						</div>
 						<div id="wp-embed-share-tab-html" class="wp-embed-share-tab" role="tabpanel" aria-labelledby="wp-embed-share-tab-button-html" aria-hidden="true">
 							<textarea class="wp-embed-share-input" tabindex="0" readonly><?php echo esc_attr( get_post_embed_html( null, 600, 400 ) ); ?></textarea>
 
 							<p class="wp-embed-share-description">
-								<?php _e( 'Copy and paste this code into your site to embed', 'oembed-api' ); ?>
+								<?php _e( 'Copy and paste this code into your site to embed' ); ?>
 							</p>
 						</div>
 					</div>
 
-					<button type="button" class="wp-embed-share-dialog-close" aria-label="<?php esc_attr_e( 'Close sharing dialog', 'oembed-api' ); ?>">
+					<button type="button" class="wp-embed-share-dialog-close" aria-label="<?php esc_attr_e( 'Close sharing dialog' ); ?>">
 						<span class="dashicons dashicons-no"></span>
 					</button>
 				</div>
@@ -216,10 +215,10 @@ if ( have_posts() ) :
 else :
 	?>
 	<div class="wp-embed">
-		<p class="wp-embed-heading"><?php _e( 'Page not found', 'oembed-api' ); ?></p>
+		<p class="wp-embed-heading"><?php _e( 'Page not found' ); ?></p>
 
 		<div class="wp-embed-excerpt">
-			<p><?php _e( 'Error 404! The requested content was not found.', 'oembed-api' ) ?></p>
+			<p><?php _e( 'Error 404! The requested content was not found.' ) ?></p>
 		</div>
 
 		<div class="wp-embed-footer">