diff --git a/src/wp-includes/media.php b/src/wp-includes/media.php
index c4aac252e4..06c27cbc7f 100644
--- a/src/wp-includes/media.php
+++ b/src/wp-includes/media.php
@@ -1206,11 +1206,13 @@ function wp_calculate_image_sizes( $size, $image_src = null, $image_meta = null,
  * @return string Converted content with 'srcset' and 'sizes' attributes added to images.
  */
 function wp_make_content_images_responsive( $content ) {
-	$images = get_media_embedded_in_content( $content, 'img' );
+	if ( ! preg_match_all( '/<img [^>]+>/', $content, $matches ) ) {
+		return $content;
+	}
 
 	$selected_images = $attachment_ids = array();
 
-	foreach( $images as $image ) {
+	foreach( $matches[0] as $image ) {
 		if ( false === strpos( $image, ' srcset=' ) && preg_match( '/wp-image-([0-9]+)/i', $image, $class_id ) &&
 			( $attachment_id = absint( $class_id[1] ) ) ) {
 
@@ -3506,12 +3508,11 @@ function get_media_embedded_in_content( $content, $types = null ) {
 	 * Filter the embedded media types that are allowed to be returned from the content blob.
 	 *
 	 * @since 4.2.0
-	 * @since 4.4.0 Added 'img' to the allowed types.
 	 *
 	 * @param array $allowed_media_types An array of allowed media types. Default media types are
-	 *                                   'audio', 'video', 'object', 'embed', 'iframe', and 'img'.
+	 *                                   'audio', 'video', 'object', 'embed', and 'iframe'.
 	 */
-	$allowed_media_types = apply_filters( 'media_embedded_in_content_allowed_types', array( 'audio', 'video', 'object', 'embed', 'iframe', 'img' ) );
+	$allowed_media_types = apply_filters( 'media_embedded_in_content_allowed_types', array( 'audio', 'video', 'object', 'embed', 'iframe' ) );
 
 	if ( ! empty( $types ) ) {
 		if ( ! is_array( $types ) ) {
diff --git a/tests/phpunit/tests/media.php b/tests/phpunit/tests/media.php
index dc5b990bd1..55a53a1eb4 100644
--- a/tests/phpunit/tests/media.php
+++ b/tests/phpunit/tests/media.php
@@ -1019,12 +1019,16 @@ EOF;
 		$img_no_width_height = str_replace( ' height="' . $size_array[1] . '"', '', $img_no_width_height );
 		$img_no_size_id = str_replace( 'wp-image-', 'id-', $img );
 		$img_with_sizes_attr = str_replace( '<img ', '<img sizes="99vw" ', $img );
+		$img_xhtml = str_replace( ' />', '/>', $img );
+		$img_html5 = str_replace( ' />', '>', $img );
 
 		// Manually add srcset and sizes to the markup from get_image_tag();
 		$respimg = preg_replace( '|<img ([^>]+) />|', '<img $1 ' . $srcset . ' ' . $sizes . ' />', $img );
 		$respimg_no_size_in_class = preg_replace( '|<img ([^>]+) />|', '<img $1 ' . $srcset . ' ' . $sizes . ' />', $img_no_size_in_class );
 		$respimg_no_width_height = preg_replace( '|<img ([^>]+) />|', '<img $1 ' . $srcset . ' ' . $sizes . ' />', $img_no_width_height );
 		$respimg_with_sizes_attr = preg_replace('|<img ([^>]+) />|', '<img $1 ' . $srcset . ' />', $img_with_sizes_attr );
+		$respimg_xhtml = preg_replace( '|<img ([^>]+)/>|', '<img $1 ' . $srcset . ' ' . $sizes . ' />', $img_xhtml );
+		$respimg_html5 = preg_replace( '|<img ([^>]+)>|', '<img $1 ' . $srcset . ' ' . $sizes . ' />', $img_html5 );
 
 		$content = '
 			<p>Image, standard. Should have srcset and sizes.</p>
@@ -1040,10 +1044,16 @@ EOF;
 			%4$s
 
 			<p>Image, with sizes attribute. Should NOT have two sizes attributes.</p>
-			%5$s';
+			%5$s
 
-		$content_unfiltered = sprintf( $content, $img, $img_no_size_in_class, $img_no_width_height, $img_no_size_id, $img_with_sizes_attr );
-		$content_filtered = sprintf( $content, $respimg, $respimg_no_size_in_class, $respimg_no_width_height, $img_no_size_id, $respimg_with_sizes_attr );
+			<p>Image, XHTML 1.0 style (no space before the closing slash). Should have srcset and sizes.</p>
+			%6$s
+
+			<p>Image, HTML 5.0 style. Should have srcset and sizes.</p>
+			%7$s';
+
+		$content_unfiltered = sprintf( $content, $img, $img_no_size_in_class, $img_no_width_height, $img_no_size_id, $img_with_sizes_attr, $img_xhtml, $img_html5 );
+		$content_filtered = sprintf( $content, $respimg, $respimg_no_size_in_class, $respimg_no_width_height, $img_no_size_id, $respimg_with_sizes_attr, $respimg_xhtml, $respimg_html5 );
 
 		$this->assertSame( $content_filtered, wp_make_content_images_responsive( $content_unfiltered ) );
 	}