diff --git a/src/tag.ts b/src/tag.ts
index 4469abf..dae679b 100644
--- a/src/tag.ts
+++ b/src/tag.ts
@@ -104,10 +104,10 @@ export function Parse(s: string): Tag {
       const value = parts[1];
       switch (key) {
         case 'type': {
-          if (!Object.values(Type).includes(value)) {
+          if (!Object.values(Type).includes(value as Type)) {
             throw new Error(`Unknown tag type attribute: ${value}`);
           }
-          tag.type = value;
+          tag.type = value as Type;
           break;
         }
         default: {