diff --git a/packages/perseus/src/perseus-types.ts b/packages/perseus/src/perseus-types.ts
index a8121c8da6..6b13316354 100644
--- a/packages/perseus/src/perseus-types.ts
+++ b/packages/perseus/src/perseus-types.ts
@@ -1074,6 +1074,7 @@ export type MathFormat =
     | "improper"
     | "proper"
     | "decimal"
+    | "percent"
     | "pi";
 
 export type PerseusNumericInputAnswerForm = {