diff --git a/src/ChronosInterface.php b/src/ChronosInterface.php
index 9238316..c5f329d 100644
--- a/src/ChronosInterface.php
+++ b/src/ChronosInterface.php
@@ -1245,7 +1245,7 @@ public function endOfWeek(): self;
      * to indicate the desired dayOfWeek, ex. static::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function next(?int $dayOfWeek = null);
 
@@ -1256,7 +1256,7 @@ public function next(?int $dayOfWeek = null);
      * to indicate the desired dayOfWeek, ex. static::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function previous(?int $dayOfWeek = null);
 
@@ -1267,7 +1267,7 @@ public function previous(?int $dayOfWeek = null);
      * to indicate the desired dayOfWeek, ex. static::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function firstOfMonth(?int $dayOfWeek = null);
 
@@ -1278,7 +1278,7 @@ public function firstOfMonth(?int $dayOfWeek = null);
      * to indicate the desired dayOfWeek, ex. static::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function lastOfMonth(?int $dayOfWeek = null);
 
@@ -1290,7 +1290,7 @@ public function lastOfMonth(?int $dayOfWeek = null);
      *
      * @param int $nth The offset to use.
      * @param int $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static|false
      */
     public function nthOfMonth(int $nth, int $dayOfWeek);
 
@@ -1301,7 +1301,7 @@ public function nthOfMonth(int $nth, int $dayOfWeek);
      * to indicate the desired dayOfWeek, ex. static::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function firstOfQuarter(?int $dayOfWeek = null);
 
@@ -1312,7 +1312,7 @@ public function firstOfQuarter(?int $dayOfWeek = null);
      * to indicate the desired dayOfWeek, ex. static::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function lastOfQuarter(?int $dayOfWeek = null);
 
@@ -1324,7 +1324,7 @@ public function lastOfQuarter(?int $dayOfWeek = null);
      *
      * @param int $nth The offset to use.
      * @param int $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static|false
      */
     public function nthOfQuarter(int $nth, int $dayOfWeek);
 
@@ -1335,7 +1335,7 @@ public function nthOfQuarter(int $nth, int $dayOfWeek);
      * to indicate the desired dayOfWeek, ex. static::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function firstOfYear(?int $dayOfWeek = null);
 
@@ -1346,7 +1346,7 @@ public function firstOfYear(?int $dayOfWeek = null);
      * to indicate the desired dayOfWeek, ex. static::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function lastOfYear(?int $dayOfWeek = null);
 
@@ -1358,7 +1358,7 @@ public function lastOfYear(?int $dayOfWeek = null);
      *
      * @param int $nth The offset to use.
      * @param int $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static|false
      */
     public function nthOfYear(int $nth, int $dayOfWeek);
 
diff --git a/src/Traits/ModifierTrait.php b/src/Traits/ModifierTrait.php
index effe09a..7fa95e4 100644
--- a/src/Traits/ModifierTrait.php
+++ b/src/Traits/ModifierTrait.php
@@ -1083,7 +1083,7 @@ public function endOfWeek(): ChronosInterface
      * to indicate the desired dayOfWeek, ex. ChronosInterface::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function next(?int $dayOfWeek = null)
     {
@@ -1103,7 +1103,7 @@ public function next(?int $dayOfWeek = null)
      * to indicate the desired dayOfWeek, ex. ChronosInterface::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function previous(?int $dayOfWeek = null)
     {
@@ -1123,7 +1123,7 @@ public function previous(?int $dayOfWeek = null)
      * to indicate the desired dayOfWeek, ex. ChronosInterface::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function firstOfMonth(?int $dayOfWeek = null)
     {
@@ -1139,7 +1139,7 @@ public function firstOfMonth(?int $dayOfWeek = null)
      * to indicate the desired dayOfWeek, ex. ChronosInterface::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function lastOfMonth(?int $dayOfWeek = null)
     {
@@ -1156,7 +1156,7 @@ public function lastOfMonth(?int $dayOfWeek = null)
      *
      * @param int $nth The offset to use.
      * @param int $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static|false
      */
     public function nthOfMonth(int $nth, int $dayOfWeek)
     {
@@ -1174,7 +1174,7 @@ public function nthOfMonth(int $nth, int $dayOfWeek)
      * to indicate the desired dayOfWeek, ex. ChronosInterface::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function firstOfQuarter(?int $dayOfWeek = null)
     {
@@ -1191,7 +1191,7 @@ public function firstOfQuarter(?int $dayOfWeek = null)
      * to indicate the desired dayOfWeek, ex. ChronosInterface::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function lastOfQuarter(?int $dayOfWeek = null)
     {
@@ -1209,7 +1209,7 @@ public function lastOfQuarter(?int $dayOfWeek = null)
      *
      * @param int $nth The offset to use.
      * @param int $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static|false
      */
     public function nthOfQuarter(int $nth, int $dayOfWeek)
     {
@@ -1228,7 +1228,7 @@ public function nthOfQuarter(int $nth, int $dayOfWeek)
      * to indicate the desired dayOfWeek, ex. ChronosInterface::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function firstOfYear(?int $dayOfWeek = null)
     {
@@ -1244,7 +1244,7 @@ public function firstOfYear(?int $dayOfWeek = null)
      * to indicate the desired dayOfWeek, ex. ChronosInterface::MONDAY.
      *
      * @param int|null $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static
      */
     public function lastOfYear(?int $dayOfWeek = null)
     {
@@ -1261,7 +1261,7 @@ public function lastOfYear(?int $dayOfWeek = null)
      *
      * @param int $nth The offset to use.
      * @param int $dayOfWeek The day of the week to move to.
-     * @return mixed
+     * @return static|false
      */
     public function nthOfYear(int $nth, int $dayOfWeek)
     {