diff --git a/src/Validation/Abstract_Validation_Rule_Builder.php b/src/Validation/Abstract_Validation_Rule_Builder.php
index 689ef67..34bc498 100644
--- a/src/Validation/Abstract_Validation_Rule_Builder.php
+++ b/src/Validation/Abstract_Validation_Rule_Builder.php
@@ -56,7 +56,7 @@ public function __construct( array $initial_rules = array() ) {
 	 *
 	 * @throws InvalidArgumentException Thrown when a forbidden rule is passed.
 	 */
-	final public function with_rule( Validation_Rule $rule ): static {
+	final public function with_rule( Validation_Rule $rule ): Validation_Rule_Builder {
 		if ( ! $this->is_allowed_rule( $rule ) ) {
 			throw new InvalidArgumentException(
 				sprintf(
diff --git a/src/Validation/Array_Validation_Rule_Builder.php b/src/Validation/Array_Validation_Rule_Builder.php
index 8d10a8f..52d851c 100644
--- a/src/Validation/Array_Validation_Rule_Builder.php
+++ b/src/Validation/Array_Validation_Rule_Builder.php
@@ -10,6 +10,7 @@
 
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Types;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Validation_Rule;
+use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Validation_Rule_Builder;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\With_Type_Support;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\Array_Validation_Rule;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\Item_Count_Range_Validation_Rule;
@@ -49,7 +50,7 @@ public function __construct( array $initial_rules = array(), bool $strict = fals
 	 *
 	 * @SuppressWarnings(PHPMD.BooleanArgumentFlag)
 	 */
-	public function with_items( Validation_Rule $item_validation_rule ): static {
+	public function with_items( Validation_Rule $item_validation_rule ): Validation_Rule_Builder {
 		return $this->with_rule( new Items_Validation_Rule( $item_validation_rule ) );
 	}
 
@@ -62,7 +63,7 @@ public function with_items( Validation_Rule $item_validation_rule ): static {
 	 * @param int $max_count Optional. Maximum count allowed. Default 0 (no limit).
 	 * @return static Builder instance for chaining.
 	 */
-	public function with_item_count_range( int $min_count = 0, int $max_count = 0 ): static {
+	public function with_item_count_range( int $min_count = 0, int $max_count = 0 ): Validation_Rule_Builder {
 		return $this->with_rule( new Item_Count_Range_Validation_Rule( $min_count, $max_count ) );
 	}
 
@@ -73,7 +74,7 @@ public function with_item_count_range( int $min_count = 0, int $max_count = 0 ):
 	 *
 	 * @return static Builder instance for chaining.
 	 */
-	public function with_unique_items(): static {
+	public function with_unique_items(): Validation_Rule_Builder {
 		return $this->with_rule( new Unique_Items_Validation_Rule() );
 	}
 
diff --git a/src/Validation/Contracts/Validation_Rule_Builder.php b/src/Validation/Contracts/Validation_Rule_Builder.php
index 7ca93bd..8289d17 100644
--- a/src/Validation/Contracts/Validation_Rule_Builder.php
+++ b/src/Validation/Contracts/Validation_Rule_Builder.php
@@ -29,7 +29,7 @@ interface Validation_Rule_Builder {
 	 *
 	 * @throws InvalidArgumentException Thrown when a forbidden rule is passed.
 	 */
-	public function with_rule( Validation_Rule $rule ): static;
+	public function with_rule( Validation_Rule $rule ): Validation_Rule_Builder;
 
 	/**
 	 * Gets the combined validation rule consisting of all rules present in the builder.
diff --git a/src/Validation/Float_Validation_Rule_Builder.php b/src/Validation/Float_Validation_Rule_Builder.php
index c513f60..bcb3102 100644
--- a/src/Validation/Float_Validation_Rule_Builder.php
+++ b/src/Validation/Float_Validation_Rule_Builder.php
@@ -10,6 +10,7 @@
 
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Types;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Validation_Rule;
+use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Validation_Rule_Builder;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\With_Type_Support;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\Datetime_Range_Validation_Rule;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\Enum_Validation_Rule;
@@ -48,7 +49,7 @@ public function __construct( array $initial_rules = array(), bool $strict = fals
 	 * @param string $regexp Regular expression to match.
 	 * @return static Builder instance for chaining.
 	 */
-	public function format_regexp( string $regexp ): static {
+	public function format_regexp( string $regexp ): Validation_Rule_Builder {
 		return $this->with_rule( new Regexp_Validation_Rule( $regexp ) );
 	}
 
@@ -61,7 +62,7 @@ public function format_regexp( string $regexp ): static {
 	 * @param string $max_datetime Optional. Maximum date-time or date allowed. Default no limit.
 	 * @return static Builder instance for chaining.
 	 */
-	public function with_datetime_range( string $min_datetime, string $max_datetime = null ): static {
+	public function with_datetime_range( string $min_datetime, string $max_datetime = null ): Validation_Rule_Builder {
 		return $this->with_rule( new Datetime_Range_Validation_Rule( $min_datetime, $max_datetime ) );
 	}
 
@@ -74,7 +75,7 @@ public function with_datetime_range( string $min_datetime, string $max_datetime
 	 * @param int|float $max Optional. Maximum value allowed. Default no limit.
 	 * @return static Builder instance for chaining.
 	 */
-	public function with_numeric_range( $min, $max = null ): static {
+	public function with_numeric_range( $min, $max = null ): Validation_Rule_Builder {
 		return $this->with_rule( new Numeric_Range_Validation_Rule( $min, $max ) );
 	}
 
@@ -89,7 +90,7 @@ public function with_numeric_range( $min, $max = null ): static {
 	 *
 	 * @SuppressWarnings(PHPMD.BooleanArgumentFlag)
 	 */
-	public function with_enum( array $allowed_values, bool $strict = false ): static {
+	public function with_enum( array $allowed_values, bool $strict = false ): Validation_Rule_Builder {
 		return $this->with_rule( new Enum_Validation_Rule( $allowed_values, $strict ) );
 	}
 
diff --git a/src/Validation/Integer_Validation_Rule_Builder.php b/src/Validation/Integer_Validation_Rule_Builder.php
index e5d452d..7a9897b 100644
--- a/src/Validation/Integer_Validation_Rule_Builder.php
+++ b/src/Validation/Integer_Validation_Rule_Builder.php
@@ -10,6 +10,7 @@
 
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Types;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Validation_Rule;
+use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Validation_Rule_Builder;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\With_Type_Support;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\Datetime_Range_Validation_Rule;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\Enum_Validation_Rule;
@@ -48,7 +49,7 @@ public function __construct( array $initial_rules = array(), bool $strict = fals
 	 * @param string $regexp Regular expression to match.
 	 * @return static Builder instance for chaining.
 	 */
-	public function format_regexp( string $regexp ): static {
+	public function format_regexp( string $regexp ): Validation_Rule_Builder {
 		return $this->with_rule( new Regexp_Validation_Rule( $regexp ) );
 	}
 
@@ -61,7 +62,7 @@ public function format_regexp( string $regexp ): static {
 	 * @param string $max_datetime Optional. Maximum date-time or date allowed. Default no limit.
 	 * @return static Builder instance for chaining.
 	 */
-	public function with_datetime_range( string $min_datetime, string $max_datetime = null ): static {
+	public function with_datetime_range( string $min_datetime, string $max_datetime = null ): Validation_Rule_Builder {
 		return $this->with_rule( new Datetime_Range_Validation_Rule( $min_datetime, $max_datetime ) );
 	}
 
@@ -74,7 +75,7 @@ public function with_datetime_range( string $min_datetime, string $max_datetime
 	 * @param int|float $max Optional. Maximum value allowed. Default no limit.
 	 * @return static Builder instance for chaining.
 	 */
-	public function with_numeric_range( $min, $max = null ): static {
+	public function with_numeric_range( $min, $max = null ): Validation_Rule_Builder {
 		return $this->with_rule( new Numeric_Range_Validation_Rule( $min, $max ) );
 	}
 
@@ -89,7 +90,7 @@ public function with_numeric_range( $min, $max = null ): static {
 	 *
 	 * @SuppressWarnings(PHPMD.BooleanArgumentFlag)
 	 */
-	public function with_enum( array $allowed_values, bool $strict = false ): static {
+	public function with_enum( array $allowed_values, bool $strict = false ): Validation_Rule_Builder {
 		return $this->with_rule( new Enum_Validation_Rule( $allowed_values, $strict ) );
 	}
 
diff --git a/src/Validation/String_Validation_Rule_Builder.php b/src/Validation/String_Validation_Rule_Builder.php
index 13b2139..94479a2 100644
--- a/src/Validation/String_Validation_Rule_Builder.php
+++ b/src/Validation/String_Validation_Rule_Builder.php
@@ -10,6 +10,7 @@
 
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Types;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Validation_Rule;
+use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\Validation_Rule_Builder;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Contracts\With_Type_Support;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\Date_Validation_Rule;
 use Felix_Arntz\WP_OOP_Plugin_Lib\Validation\Rules\Datetime_Range_Validation_Rule;
@@ -52,7 +53,7 @@ public function __construct( array $initial_rules = array(), bool $strict = fals
 	 *
 	 * @return static Builder instance for chaining.
 	 */
-	public function format_date(): static {
+	public function format_date(): Validation_Rule_Builder {
 		return $this->with_rule( new Date_Validation_Rule() );
 	}
 
@@ -63,7 +64,7 @@ public function format_date(): static {
 	 *
 	 * @return static Builder instance for chaining.
 	 */
-	public function format_datetime(): static {
+	public function format_datetime(): Validation_Rule_Builder {
 		return $this->with_rule( new Datetime_Validation_Rule() );
 	}
 
@@ -74,7 +75,7 @@ public function format_datetime(): static {
 	 *
 	 * @return static Builder instance for chaining.
 	 */
-	public function format_email(): static {
+	public function format_email(): Validation_Rule_Builder {
 		return $this->with_rule( new Email_Validation_Rule() );
 	}
 
@@ -85,7 +86,7 @@ public function format_email(): static {
 	 *
 	 * @return static Builder instance for chaining.
 	 */
-	public function format_version(): static {
+	public function format_version(): Validation_Rule_Builder {
 		return $this->with_rule( new Version_Validation_Rule() );
 	}
 
@@ -96,7 +97,7 @@ public function format_version(): static {
 	 *
 	 * @return static Builder instance for chaining.
 	 */
-	public function format_hex_color(): static {
+	public function format_hex_color(): Validation_Rule_Builder {
 		return $this->with_rule( new Hex_Color_Validation_Rule() );
 	}
 
@@ -108,7 +109,7 @@ public function format_hex_color(): static {
 	 * @param string $regexp Regular expression to match.
 	 * @return static Builder instance for chaining.
 	 */
-	public function format_regexp( string $regexp ): static {
+	public function format_regexp( string $regexp ): Validation_Rule_Builder {
 		return $this->with_rule( new Regexp_Validation_Rule( $regexp ) );
 	}
 
@@ -119,7 +120,7 @@ public function format_regexp( string $regexp ): static {
 	 *
 	 * @return static Builder instance for chaining.
 	 */
-	public function format_url(): static {
+	public function format_url(): Validation_Rule_Builder {
 		return $this->with_rule( new URL_Validation_Rule() );
 	}
 
@@ -132,7 +133,7 @@ public function format_url(): static {
 	 * @param string $max_datetime Optional. Maximum date-time or date allowed. Default no limit.
 	 * @return static Builder instance for chaining.
 	 */
-	public function with_datetime_range( string $min_datetime, string $max_datetime = null ): static {
+	public function with_datetime_range( string $min_datetime, string $max_datetime = null ): Validation_Rule_Builder {
 		return $this->with_rule( new Datetime_Range_Validation_Rule( $min_datetime, $max_datetime ) );
 	}
 
@@ -147,7 +148,7 @@ public function with_datetime_range( string $min_datetime, string $max_datetime
 	 *
 	 * @SuppressWarnings(PHPMD.BooleanArgumentFlag)
 	 */
-	public function with_enum( array $allowed_values, bool $strict = false ): static {
+	public function with_enum( array $allowed_values, bool $strict = false ): Validation_Rule_Builder {
 		return $this->with_rule( new Enum_Validation_Rule( $allowed_values, $strict ) );
 	}