diff --git a/src/contract/assembled_transaction.ts b/src/contract/assembled_transaction.ts
index a6664d6e1..9cf5c2c99 100644
--- a/src/contract/assembled_transaction.ts
+++ b/src/contract/assembled_transaction.ts
@@ -330,8 +330,8 @@ export class AssembledTransaction<T> {
       method: this.options.method,
       tx: this.built?.toXDR(),
       simulationResult: {
-        auth: this.simulationData.result?.auth.map((a) => a.toXDR("base64")),
-        retval: this.simulationData.result?.retval.toXDR("base64"),
+        auth: this.simulationData.result.auth.map((a) => a.toXDR("base64")),
+        retval: this.simulationData.result.retval.toXDR("base64"),
       },
       simulationTransactionData:
         this.simulationData.transactionData.toXDR("base64"),
@@ -532,7 +532,7 @@ export class AssembledTransaction<T> {
   };
 
   get simulationData(): {
-    result?: Api.SimulateHostFunctionResult;
+    result: Api.SimulateHostFunctionResult;
     transactionData: xdr.SorobanTransactionData;
   } {
     if (this.simulationResult && this.simulationTransactionData) {
@@ -560,7 +560,7 @@ export class AssembledTransaction<T> {
     }
 
     // add to object for serialization & deserialization
-    this.simulationResult = simulation.result;
+    this.simulationResult = simulation.result ?? { auth: [], retval: new xdr.ScVal() };
     this.simulationTransactionData = simulation.transactionData.build();
 
     return {
@@ -574,7 +574,7 @@ export class AssembledTransaction<T> {
       if (!this.simulationData.result) {
         throw new Error("No simulation result!");
       }
-      return this.options.parseResultXdr(this.simulationData.result?.retval);
+      return this.options.parseResultXdr(this.simulationData.result.retval);
     } catch (e) {
       if (!implementsToString(e)) throw e;
       const err = this.parseError(e.toString());
@@ -827,7 +827,7 @@ export class AssembledTransaction<T> {
    * returns `false`, then you need to call `signAndSend` on this transaction.
    */
   get isReadCall(): boolean {
-    const authsCount = this.simulationData.result?.auth.length;
+    const authsCount = this.simulationData.result.auth.length;
     const writeLength = this.simulationData.transactionData
       .resources()
       .footprint()