diff --git a/src/SlugOptions.php b/src/SlugOptions.php
index 111d104..f159e65 100644
--- a/src/SlugOptions.php
+++ b/src/SlugOptions.php
@@ -63,6 +63,7 @@ class SlugOptions implements \IteratorAggregate
 	public function __construct(iterable $options = [])
 	{
 		foreach ($options as $option => $value) {
+			$this->assertOptionName($option);
 			$this->{'set'.ucfirst($option)}($value);
 		}
 	}
@@ -95,6 +96,7 @@ public function merge(iterable $options): self
 		$merged = clone $this;
 
 		foreach ($options as $option => $value) {
+			$this->assertOptionName($option);
 			$merged->{'set'.ucfirst($option)}($value);
 		}
 
@@ -291,6 +293,28 @@ public function setPostTransforms(iterable $transforms): self
 		return $this->setTransforms(array_merge($this->transforms, $transforms));
 	}
 
+	/**
+	 * @param string $option
+	 *
+	 * @throws \InvalidArgumentException If it’s an invalid option name
+	 */
+	private function assertOptionName(string $option): void
+	{
+		static $validOptions = [
+			'delimiter',
+			'valid',
+			'ignore',
+			'locale',
+			'transforms',
+			'preTransforms',
+			'postTransforms',
+		];
+
+		if (!in_array($option, $validOptions, true)) {
+			throw new \InvalidArgumentException(sprintf('Unknown option "%s"', $option));
+		}
+	}
+
 	/**
 	 * @param string $chars
 	 *
diff --git a/tests/SlugOptionsTest.php b/tests/SlugOptionsTest.php
index f824be5..e48ac7d 100644
--- a/tests/SlugOptionsTest.php
+++ b/tests/SlugOptionsTest.php
@@ -292,4 +292,12 @@ public function getAddTransformThrows()
 			[new \stdClass, \TypeError::class],
 		];
 	}
+
+	public function testUnknownOptionThrows()
+	{
+		$this->expectException(\InvalidArgumentException::class);
+		$this->expectExceptionMessageRegExp('(unknown.*"foo")i');
+
+		new SlugOptions(['foo' => 'bar']);
+	}
 }