diff --git a/src/Azvyl/PMServerUI/ddui/CustomForm.php b/src/Azvyl/PMServerUI/ddui/CustomForm.php
index 449be2a..5e89751 100644
--- a/src/Azvyl/PMServerUI/ddui/CustomForm.php
+++ b/src/Azvyl/PMServerUI/ddui/CustomForm.php
@@ -64,7 +64,7 @@ public static function create(Player $player, Observable|string|UIRawMessage $ti
 	 * @param Observable<string>|Observable<UIRawMessage>|string|UIRawMessage|null $tooltip The tooltip to display when hovering over the button.
 	 * @param bool|Observable<bool> $visible
 	 */
-	public function button(Observable|string|UIRawMessage $label, callable $onClick, bool|Observable $disabled = null, Observable|string|UIRawMessage $tooltip = null, bool|Observable $visible = null) : self{
+	public function button(Observable|string|UIRawMessage $label, callable $onClick, bool|Observable|null $disabled = null, Observable|string|UIRawMessage|null $tooltip = null, bool|Observable|null $visible = null) : self{
 		$this->elements[] = new ButtonElement($label, $onClick, $disabled, $tooltip, $visible);
 		return $this;
 	}
@@ -98,7 +98,7 @@ public function closeButton() : self{
 	 *
 	 * @param bool|Observable<bool> $visible Whether the divider is visible.
 	 */
-	public function divider(bool|Observable $visible = null) : self{
+	public function divider(bool|Observable|null $visible = null) : self{
 		$this->elements[] = new DividerElement($visible);
 		return $this;
 	}
@@ -114,7 +114,7 @@ public function divider(bool|Observable $visible = null) : self{
 	 * @param bool|Observable<bool> $disabled
 	 * @param bool|Observable<bool> $visible
 	 */
-	public function dropdown(Observable|string|UIRawMessage $label, Observable $value, array $items, Observable|string|UIRawMessage $description = null, bool|Observable $disabled = null, bool|Observable $visible = null) : self{ // TODO: verify if $description can be Observable<UIRawMessage>
+	public function dropdown(Observable|string|UIRawMessage $label, Observable $value, array $items, Observable|string|UIRawMessage|null $description = null, bool|Observable|null $disabled = null, bool|Observable|null $visible = null) : self{ // TODO: verify if $description can be Observable<UIRawMessage>
 		$this->elements[] = new DropdownElement($label, $value, $items, $description, $disabled, $visible);
 		return $this;
 	}
@@ -125,7 +125,7 @@ public function dropdown(Observable|string|UIRawMessage $label, Observable $valu
 	 * @param Observable<string>|Observable<UIRawMessage>|string|UIRawMessage $text The text to display in the label.
 	 * @param bool|Observable<bool> $visible
 	 */
-	public function label(Observable|string|UIRawMessage $text, bool|Observable $visible = null) : self{
+	public function label(Observable|string|UIRawMessage $text, bool|Observable|null $visible = null) : self{
 		$this->elements[] = new LabelElement($text, $visible);
 		return $this;
 	}
@@ -136,7 +136,7 @@ public function label(Observable|string|UIRawMessage $text, bool|Observable $vis
 	 * @param Observable<string>|Observable<UIRawMessage>|string|UIRawMessage $text The text to display in the header.
 	 * @param bool|Observable<bool> $visible Whether the header is visible.
 	 */
-	public function header(Observable|string|UIRawMessage $text, bool|Observable $visible = null) : self{
+	public function header(Observable|string|UIRawMessage $text, bool|Observable|null $visible = null) : self{
 		$this->elements[] = new HeaderElement($text, $visible);
 		return $this;
 	}
@@ -199,7 +199,7 @@ public function show() : Promise{ // TODO: return Promise<DataDrivenScreenClosed
 	 * @param Observable<int>|Observable<float>|int|float|null $step The step size (increment) for the slider.
 	 * @param bool|Observable<bool>|null $visible
 	 */
-	public function slider(Observable|string|UIRawMessage $label, Observable $value, int|float|Observable $minValue, int|float|Observable $maxValue, Observable|string|UIRawMessage $description = null, bool|Observable $disabled = null, int|float|Observable $step = null, bool|Observable $visible = null) : self{
+	public function slider(Observable|string|UIRawMessage $label, Observable $value, int|float|Observable $minValue, int|float|Observable $maxValue, Observable|string|UIRawMessage|null $description = null, bool|Observable|null $disabled = null, int|float|Observable|null $step = null, bool|Observable|null $visible = null) : self{
 		$this->elements[] = new SliderElement($label, $value, $minValue, $maxValue, $description, $disabled, $step, $visible);
 		return $this;
 	}
@@ -209,7 +209,7 @@ public function slider(Observable|string|UIRawMessage $label, Observable $value,
 	 *
 	 * @param bool|Observable<bool>|null $visible Whether the spacer is visible.
 	 */
-	public function spacer(bool|Observable $visible = null) : self{
+	public function spacer(bool|Observable|null $visible = null) : self{
 		$this->elements[] = new SpacerElement($visible);
 		return $this;
 	}
@@ -223,7 +223,7 @@ public function spacer(bool|Observable $visible = null) : self{
 	 * @param bool|Observable<bool>|null $disabled
 	 * @param bool|Observable<bool>|null $visible
 	 */
-	public function textField(Observable|string|UIRawMessage $label, Observable $text, Observable|string|UIRawMessage $description = null, bool|Observable $disabled = null, bool|Observable $visible = null) : self{
+	public function textField(Observable|string|UIRawMessage $label, Observable $text, Observable|string|UIRawMessage|null $description = null, bool|Observable|null $disabled = null, bool|Observable|null $visible = null) : self{
 		$this->elements[] = new TextFieldElement($label, $text, $description, $disabled, $visible);
 		return $this;
 	}
@@ -237,7 +237,7 @@ public function textField(Observable|string|UIRawMessage $label, Observable $tex
 	 * @param bool|Observable<bool>|null $disabled
 	 * @param bool|Observable<bool>|null $visible
 	 */
-	public function toggle(Observable|string|UIRawMessage $label, Observable $toggled, Observable|string|UIRawMessage $description = null, bool|Observable $disabled = null, bool|Observable $visible = null) : self{
+	public function toggle(Observable|string|UIRawMessage $label, Observable $toggled, Observable|string|UIRawMessage|null $description = null, bool|Observable|null $disabled = null, bool|Observable|null $visible = null) : self{
 		$this->elements[] = new ToggleElement($label, $toggled, $description, $disabled, $visible);
 		return $this;
 	}
diff --git a/src/Azvyl/PMServerUI/ui/ActionFormData.php b/src/Azvyl/PMServerUI/ui/ActionFormData.php
index ceb5ae3..fd49f45 100644
--- a/src/Azvyl/PMServerUI/ui/ActionFormData.php
+++ b/src/Azvyl/PMServerUI/ui/ActionFormData.php
@@ -64,7 +64,7 @@ public function toPacketFormData() : array{
 	}
 
 	/** @internal */
-	public function processResponse(string $rawData = null, FormCancelationReason $cancelReason = null) : ActionFormResponse{
+	public function processResponse(?string $rawData = null, ?FormCancelationReason $cancelReason = null) : ActionFormResponse{
 		if($cancelReason !== null){
 			return new ActionFormResponse($cancelReason, null);
 		}
diff --git a/src/Azvyl/PMServerUI/ui/MessageFormData.php b/src/Azvyl/PMServerUI/ui/MessageFormData.php
index 7208150..4ae0f38 100644
--- a/src/Azvyl/PMServerUI/ui/MessageFormData.php
+++ b/src/Azvyl/PMServerUI/ui/MessageFormData.php
@@ -46,7 +46,7 @@ public function toPacketFormData() : array{
 	}
 
 	/** @internal */
-	public function processResponse(string $rawData = null, FormCancelationReason $cancelReason = null) : MessageFormResponse{
+	public function processResponse(?string $rawData = null, ?FormCancelationReason $cancelReason = null) : MessageFormResponse{
 		if($cancelReason !== null){
 			return new MessageFormResponse($cancelReason, null);
 		}
diff --git a/src/Azvyl/PMServerUI/ui/ModalFormData.php b/src/Azvyl/PMServerUI/ui/ModalFormData.php
index fce9fac..3814c39 100644
--- a/src/Azvyl/PMServerUI/ui/ModalFormData.php
+++ b/src/Azvyl/PMServerUI/ui/ModalFormData.php
@@ -43,7 +43,7 @@ public function divider() : self{
 	/**
 	 * @param string[]|UIRawMessage[] $items
 	 */
-	public function dropdown(string|UIRawMessage $label, array $items, int $defaultIndex = null, string|UIRawMessage $tooltip = null) : self{
+	public function dropdown(string|UIRawMessage $label, array $items, ?int $defaultIndex = null, string|UIRawMessage|null $tooltip = null) : self{
 		$dropdownElement = [
 			'type' => 'dropdown',
 			'text' => $label instanceof UIRawMessage ? $label->encode() : $label,
@@ -83,7 +83,7 @@ public function label(string|UIRawMessage $text) : self{
 		return $this;
 	}
 
-	public function slider(string|UIRawMessage $label, int $min, int $max, int $default = null, string|UIRawMessage $tooltip = null, int $step = null) : self{
+	public function slider(string|UIRawMessage $label, int $min, int $max, ?int $default = null, string|UIRawMessage|null $tooltip = null, ?int $step = null) : self{
 		$sliderElement = [
 			'type' => 'slider',
 			'text' => $label instanceof UIRawMessage ? $label->encode() : $label,
@@ -118,7 +118,7 @@ public function submitButton(string|UIRawMessage $text) : self{
 		return $this;
 	}
 
-	public function textField(string|UIRawMessage $label, string|UIRawMessage $placeholderText = null, string|UIRawMessage $default = null, string|UIRawMessage $tooltip = null) : self{
+	public function textField(string|UIRawMessage $label, string|UIRawMessage|null $placeholderText = null, string|UIRawMessage|null $default = null, string|UIRawMessage|null $tooltip = null) : self{
 		$textFieldElement = [
 			'type' => 'input',
 			'text' => $label instanceof UIRawMessage ? $label->encode() : $label,
@@ -141,7 +141,7 @@ public function textField(string|UIRawMessage $label, string|UIRawMessage $place
 		return $this;
 	}
 
-	public function toggle(string|UIRawMessage $label, bool $default = null, string|UIRawMessage $tooltip = null) : self{
+	public function toggle(string|UIRawMessage $label, ?bool $default = null, string|UIRawMessage|null $tooltip = null) : self{
 		$toggleElement = [
 			'type' => 'toggle',
 			'text' => $label instanceof UIRawMessage ? $label->encode() : $label,
@@ -178,7 +178,7 @@ public function toPacketFormData() : array{
 	}
 
 	/** @internal */
-	public function processResponse(string $rawData = null, FormCancelationReason $cancelReason = null) : ModalFormResponse{
+	public function processResponse(?string $rawData = null, ?FormCancelationReason $cancelReason = null) : ModalFormResponse{
 		if($cancelReason !== null){
 			return new ModalFormResponse($cancelReason, null);
 		}
diff --git a/src/Azvyl/PMServerUI/ui/ServerUI.php b/src/Azvyl/PMServerUI/ui/ServerUI.php
index f4dea20..6bdb5b1 100644
--- a/src/Azvyl/PMServerUI/ui/ServerUI.php
+++ b/src/Azvyl/PMServerUI/ui/ServerUI.php
@@ -25,6 +25,6 @@ final public function show(Player $player) : Promise{
 
 	abstract public function toPacketFormData() : array;
 
-	abstract public function processResponse(string $rawData = null, FormCancelationReason $cancelReason = null) : FormResponse;
+	abstract public function processResponse(?string $rawData = null, ?FormCancelationReason $cancelReason = null) : FormResponse;
 
 }
\ No newline at end of file