diff --git a/src/api/js/src/high-level/high-level.ts b/src/api/js/src/high-level/high-level.ts
index 74a3a9d2d..a5e27429b 100644
--- a/src/api/js/src/high-level/high-level.ts
+++ b/src/api/js/src/high-level/high-level.ts
@@ -503,7 +503,8 @@ export function createApi(Z3: Z3Core): Z3HighLevel {
     ///////////////////////////////
 
     async function simplify(e : Expr<Name>) {
-       return _toExpr(check(Z3.simplify(contextPtr, e.ast)));
+       const result = await Z3.simplify(contextPtr, e.ast)       
+       return _toExpr(check(result));
     }
 
     /////////////