diff --git a/.changeset/nice-poets-attack.md b/.changeset/nice-poets-attack.md
new file mode 100644
index 000000000..e338d298c
--- /dev/null
+++ b/.changeset/nice-poets-attack.md
@@ -0,0 +1,5 @@
+---
+'@openfn/runtime': patch
+---
+
+Fix an issue where expression result state is not serialized before being broadcast, causing blowups
diff --git a/packages/runtime/src/execute/expression.ts b/packages/runtime/src/execute/expression.ts
index da9a914e8..97091cc0d 100644
--- a/packages/runtime/src/execute/expression.ts
+++ b/packages/runtime/src/execute/expression.ts
@@ -66,14 +66,16 @@ export default (
 
       duration = Date.now() - duration;
 
+      const finalState = prepareFinalState(opts, result);
+
       notify(NOTIFY_JOB_COMPLETE, {
         duration,
-        state: result,
+        state: finalState,
         jobId: id,
       });
 
       // return the final state
-      resolve(prepareFinalState(opts, result));
+      resolve(finalState);
     } catch (e: any) {
       duration = Date.now() - duration;
       let finalError;