diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index c6542d62d9..ce45499d0c 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -797,7 +797,8 @@ function wp_get_http_headers( $url, $deprecated = false ) {
  */
 function is_new_day() {
 	global $currentday, $previousday;
-	if ( $currentday != $previousday ) {
+
+	if ( $currentday !== $previousday ) {
 		return 1;
 	} else {
 		return 0;
diff --git a/tests/phpunit/tests/functions/isNewDay.php b/tests/phpunit/tests/functions/isNewDay.php
new file mode 100644
index 0000000000..629a6d3de5
--- /dev/null
+++ b/tests/phpunit/tests/functions/isNewDay.php
@@ -0,0 +1,36 @@
+<?php
+/**
+ * Test is_new_date() function.
+ *
+ * @since 5.2.0
+ *
+ * @group functions.php
+ */
+class Tests_Functions_is_new_date extends WP_UnitTestCase {
+
+	/**
+	 * @ticket 46627
+	 * @dataProvider _data_is_new_date
+	 *
+	 * @param string $currentday_string  The day of the current post in the loop.
+	 * @param string $previousday_string The day of the previous post in the loop.
+	 * @param bool   $expected           Expected result.
+	 */
+	public function test_is_new_date( $currentday_string, $previousday_string, $expected ) {
+		global $currentday, $previousday;
+
+		$currentday  = $currentday_string;
+		$previousday = $previousday_string;
+
+		$this->assertSame( $expected, is_new_day() );
+	}
+
+	public function _data_is_new_date() {
+		return array(
+			array( '21.05.19', '21.05.19', 0 ),
+			array( '21.05.19', '20.05.19', 1 ),
+			array( '21.05.19', false, 1 ),
+		);
+	}
+
+}