diff --git a/lib/types/report-types.js b/lib/types/report-types.js
--- a/lib/types/report-types.js
+++ b/lib/types/report-types.js
@@ -245,16 +245,17 @@
   +payload: $ReadOnlyArray<BaseAction>,
 };
 
-const tActionSummary = tShape<ActionSummary>({
-  type: t.String,
-  time: t.Number,
-  summary: t.String,
-});
 const tActionType = t.irreducible<$PropertyType<BaseAction, 'type'>>(
   'ActionType',
   x => typeof x === 'string',
 );
 
+const tActionSummary = tShape<ActionSummary>({
+  type: tActionType,
+  time: t.Number,
+  summary: t.String,
+});
+
 export const threadInconsistencyReportValidatorShape: TStructProps<ThreadInconsistencyReportShape> =
   {
     platformDetails: tPlatformDetails,