diff --git a/src/parse.js b/src/parse.js
index 140c7a07..8c5cfa55 100644
--- a/src/parse.js
+++ b/src/parse.js
@@ -216,7 +216,7 @@ export function tokenize(str = '') {
 			let alpha;
 			if (is_num(chars)) {
 				alpha = num(chars);
-				if (alpha.type !== Tok.Hue) {
+				if (alpha !== undefined && alpha.type !== Tok.Hue) {
 					tokens.push({ type: Tok.Alpha, value: alpha });
 					continue;
 				}
@@ -251,7 +251,7 @@ export function tokenize(str = '') {
 		return undefined;
 	}
 
-	return tokens;
+	return tokens.includes(undefined) ? undefined : tokens;
 }
 
 export function parseColorSyntax(tokens) {
diff --git a/test/parse.test.js b/test/parse.test.js
index 6f1fd072..bd65c085 100644
--- a/test/parse.test.js
+++ b/test/parse.test.js
@@ -408,3 +408,17 @@ test('undefined', t => {
 test('Issue #204', t => {
 	assert.equal(parse('oklch(70% 0..1 156)'), undefined);
 });
+
+test('invalid dimension does not throw', t => {
+	const tests = [
+		'rgb(1px 2 3)',
+		'hsl(90DEG 100% 50%)',
+		'oklab(1x 2 3)',
+		'lch(50% 40 90DEG)',
+		'color(srgb 1 2px 3)',
+		'rgb(1 2 3 / 1px)'
+	];
+	tests.forEach(t => {
+		assert.equal(parse(t), undefined, t);
+	});
+});