diff --git a/packages/comms/src/ecl/dfuWorkunit.ts b/packages/comms/src/ecl/dfuWorkunit.ts
index f80a4468e3..f30f1f3cbb 100644
--- a/packages/comms/src/ecl/dfuWorkunit.ts
+++ b/packages/comms/src/ecl/dfuWorkunit.ts
@@ -214,7 +214,7 @@ export class DFUWorkunit extends StateObject<UDFUWorkunitState, IDFUWorkunitStat
         return this;
     }
 
-    fetchXML(callback?: void): Promise<FileSpray.DFUWUFileResponse> {
+    fetchXML(callback?: void): Promise<string> {
         return this.DFUWUFile();
     }
 
@@ -239,14 +239,14 @@ export class DFUWorkunit extends StateObject<UDFUWorkunitState, IDFUWorkunitStat
         return retVal;
     }
 
-    protected DFUWUFile(_request: Partial<FileSpray.DFUWUFileRequest> = {}): Promise<FileSpray.DFUWUFileResponse> {
-        return this.connection.DFUWUFile({
+    protected DFUWUFile(_request: Partial<FileSpray.DFUWUFileRequest> = {}): Promise<string> {
+        return this.connection.DFUWUFileEx({
             ..._request, Wuid: this.ID
         }).then(response => {
             //TODO: additional processing?
             return response;
         }).catch((e: ESPExceptions) => {
-            return {} as FileSpray.DFUWUFileResponse;
+            return "";
         });
     }
 
diff --git a/packages/comms/src/services/fileSpray.ts b/packages/comms/src/services/fileSpray.ts
index 2922d202ac..128e761fc8 100644
--- a/packages/comms/src/services/fileSpray.ts
+++ b/packages/comms/src/services/fileSpray.ts
@@ -13,6 +13,10 @@ export interface UpdateDFUWorkunitEx extends UpdateDFUWorkunitMinusWU {
 
 export class FileSprayService extends FileSprayServiceBase {
 
+    DFUWUFileEx(request: FileSpray.DFUWUFileRequest): Promise<string> {
+        return this._connection.send("DFUWUFile", request, "text");
+    }
+
     SprayFixedEx(request: Partial<FileSpray.SprayFixed>): Promise<FileSpray.SprayFixedResponse> {
         return this._connection.send("SprayFixed", request);
     }