diff --git a/source/index.ts b/source/index.ts
index 9bed5cc..7e68ccb 100644
--- a/source/index.ts
+++ b/source/index.ts
@@ -170,7 +170,7 @@ is.array = <T = unknown>(value: unknown, assertion?: (value: T) => value is T):
 		return false;
 	}
 
-	if (!assertion) {
+	if (!is.function_(assertion)) {
 		return true;
 	}
 
diff --git a/test/test.ts b/test/test.ts
index 16e376c..c5c98cd 100644
--- a/test/test.ts
+++ b/test/test.ts
@@ -1537,6 +1537,8 @@ test('is.all', t => {
 	t.false(is.all(is.string, '🦄', []));
 	t.false(is.all(is.set, new Map(), {}));
 
+	t.true(is.all(is.array, ...[['1'], ['2']]));
+
 	t.throws(() => {
 		is.all(null as any, true);
 	});