diff --git a/src/Liquid/StandardFilters.php b/src/Liquid/StandardFilters.php
index 086b517f..2e7d62e7 100644
--- a/src/Liquid/StandardFilters.php
+++ b/src/Liquid/StandardFilters.php
@@ -410,13 +410,13 @@ public static function prepend($input, $string)
 	 * Remove a substring
 	 *
 	 * @param string $input
-	 * @param string $string
+	 * @param string|null $string
 	 *
 	 * @return string
 	 */
 	public static function remove($input, $string)
 	{
-		return str_replace($string, '', $input);
+		return self::replace($input, $string);
 	}
 
 
@@ -441,15 +441,18 @@ public static function remove_first($input, $string)
 	/**
 	 * Replace occurrences of a string with another
 	 *
-	 * @param string $input
-	 * @param string $string
-	 * @param string $replacement
+	 * @param string|null $input
+	 * @param string|null $string
+	 * @param string|null $replacement
 	 *
 	 * @return string
 	 */
 	public static function replace($input, $string, $replacement = '')
 	{
-		return str_replace($string, $replacement, $input);
+		if ($string === null) {
+			return $input;
+		}
+		return str_replace($string, (string)$replacement, (string)$input);
 	}
 
 
diff --git a/tests/Liquid/OutputTest.php b/tests/Liquid/OutputTest.php
index de035b73..f10519da 100644
--- a/tests/Liquid/OutputTest.php
+++ b/tests/Liquid/OutputTest.php
@@ -224,4 +224,18 @@ public function testFilterArrayNull()
 
 		$this->assertTemplateResult($expected, $text, []);
 	}
+
+	public function testRemoveWithNull(): void
+	{
+		$text = ' {{ best_cars | remove: brand }} ';
+
+		$this->assertTemplateResult(' bmw ', $text, [...$this->assigns, 'brand' => null]);
+	}
+
+	public function testReplaceWithNull()
+	{
+		$text = ' {{ best_cars | replace: brand }} ';
+
+		$this->assertTemplateResult(' bmw ', $text, [...$this->assigns, 'brand' => null]);
+	}
 }