diff --git a/src/wp-includes/pluggable.php b/src/wp-includes/pluggable.php
index 0c871388b2..468b92610e 100644
--- a/src/wp-includes/pluggable.php
+++ b/src/wp-includes/pluggable.php
@@ -2181,7 +2181,7 @@ function get_avatar( $id_or_email, $size = 96, $default = '', $alt = '', $args =
 	}
 
 	$avatar = sprintf(
-		'<img alt="%s" src="%s" class="%s" height="%d" width="%d" />',
+		"<img alt='%s' src='%s' class='%s' height='%d' width='%d' />",
 		esc_attr( $args['alt'] ),
 		esc_url( $url ),
 		esc_attr( join( ' ', $class ) ),
diff --git a/tests/phpunit/tests/avatar.php b/tests/phpunit/tests/avatar.php
index 50aca9cd5f..b9a94ee003 100755
--- a/tests/phpunit/tests/avatar.php
+++ b/tests/phpunit/tests/avatar.php
@@ -166,30 +166,30 @@ class Tests_Avatar extends WP_UnitTestCase {
 
 	public function test_get_avatar() {
 		$img = get_avatar( 1 );
-		$this->assertEquals( preg_match( '|^<img alt="[^"]*" src="[^"]*" class="[^"]*" height="[^"]*" width="[^"]*" />$|', $img ), 1 );
+		$this->assertEquals( preg_match( "|^<img alt='[^']*' src='[^']*' class='[^']*' height='[^']*' width='[^']*' />$|", $img ), 1 );
 	}
 
 	public function test_get_avatar_size() {
 		$size = '100';
 		$img = get_avatar( 1, $size );
-		$this->assertEquals( preg_match( '|^<img .*height="' . $size . '".*width="' . $size . '"|', $img ), 1 );
+		$this->assertEquals( preg_match( "|^<img .*height='$size'.*width='$size'|", $img ), 1 );
 	}
 
 	public function test_get_avatar_alt() {
 		$alt = 'Mr Hyde';
 		$img = get_avatar( 1, 96, '', $alt );
-		$this->assertEquals( preg_match( '|^<img alt="' . $alt . '"|', $img ), 1 );
+		$this->assertEquals( preg_match( "|^<img alt='$alt'|", $img ), 1 );
 	}
 
 	public function test_get_avatar_class() {
 		$class = 'first';
 		$img = get_avatar( 1, 96, '', '', array( 'class' => $class ) );
-		$this->assertEquals( preg_match( '|^<img .*class="[^"]*' . $class . '[^"]*"|', $img ), 1 );
+		$this->assertEquals( preg_match( "|^<img .*class='[^']*{$class}[^']*'|", $img ), 1 );
 	}
 
 	public function test_get_avatar_default_class() {
 		$img = get_avatar( 1, 96, '', '', array( 'force_default' => true ) );
-		$this->assertEquals( preg_match( '|^<img .*class="[^"]*avatar-default[^"]*"|', $img ), 1 );
+		$this->assertEquals( preg_match( "|^<img .*class='[^']*avatar-default[^']*'|", $img ), 1 );
 	}
 
 	public function test_get_avatar_force_display() {