diff --git src/wp-includes/functions.php src/wp-includes/functions.php
index 6c5184f697..01bf984624 100644
--- src/wp-includes/functions.php
+++ src/wp-includes/functions.php
@@ -591,7 +591,7 @@ function get_weekstartend( $mysqlstring, $start_of_week = '' ) {
  */
 function maybe_unserialize( $original ) {
 	if ( is_serialized( $original ) ) { // Don't attempt to unserialize data that wasn't serialized going in.
-		return @unserialize( $original );
+		return @unserialize( trim( $original ) );
 	}
 	return $original;
 }
diff --git tests/phpunit/tests/functions/maybe_unserialize.php tests/phpunit/tests/functions/maybe_unserialize.php
new file mode 100644
index 0000000000..5ff83fc6ce
--- /dev/null
+++ tests/phpunit/tests/functions/maybe_unserialize.php
@@ -0,0 +1,78 @@
+<?php
+/**
+ * Test functions against maybe_unserialize.
+ * Tested scenarios:
+ *     1)
+ * @group functions.php
+ */
+
+if ( ! defined( 'WPINC' ) ) {
+	die;
+}
+
+
+class Tests_Functions_maybe_unserialize extends WP_UnitTestCase {
+
+	//Passing an array should return the same array back
+	public function test_maybe_unserialize_array() {
+		$expected = array(
+			'start' => 'here',
+			'end'   => 'here',
+		);
+
+		$this->assertEquals( $expected, maybe_unserialize( $expected ) );
+	}
+
+	//Tests normal string unserialization
+	public function test_maybe_unserialize_string() {
+		$this->assertEquals( 'string', maybe_unserialize( 'string' ) );
+
+		$this->assertEquals( '[string]', maybe_unserialize( '[string]' ) );
+
+		$this->assertEquals( '{s:5:"start";s:4:"here";s:3:"end";s:4:"here";}', maybe_unserialize( '{s:5:"start";s:4:"here";s:3:"end";s:4:"here";}' ) );
+
+	}
+
+	//Passing an int should return the same int
+	public function test_maybe_unserialize_int() {
+
+		$this->assertEquals( 100, maybe_unserialize( 100 ) );
+	}
+
+	//Passing null should return null
+	public function test_maybe_unserialize_null() {
+
+		$this->assertEquals( null, maybe_unserialize( null ) );
+	}
+
+	//Passing null should return null
+	public function test_maybe_unserialize_object() {
+		$object = new stdClass();
+
+		$this->assertEquals( $object, maybe_unserialize( $object ) );
+	}
+
+	public function test_maybe_unserialize_to_array() {
+		$expected = array(
+			'start' => 'here',
+			'end'   => 'here',
+		);
+
+		$this->assertEquals( $expected, maybe_unserialize( 'a:2:{s:5:"start";s:4:"here";s:3:"end";s:4:"here";}' ) );
+	}
+
+	public function test_maybe_unserialize_bad_serialized_string() {
+
+		// a:3 not a:2 as it should be
+		$this->assertFalse( maybe_unserialize( 'a:3:{s:5:"start";s:4:"here";s:3:"end";s:4:"here";}' ) );
+	}
+
+	public function test_maybe_unserialize_to_array_un_trimed() {
+		$expected = array(
+			'start' => 'here',
+			'end'   => 'here',
+		);
+
+		$this->assertEquals( $expected, maybe_unserialize( '    a:2:{s:5:"start";s:4:"here";s:3:"end";s:4:"here";}     ' ) );
+	}
+}
\ No newline at end of file