diff --git a/api/src/utils/normalize.test.ts b/api/src/utils/normalize.test.ts
index ee0267dda04..831eaa2dcc3 100644
--- a/api/src/utils/normalize.test.ts
+++ b/api/src/utils/normalize.test.ts
@@ -193,6 +193,10 @@ describe('normalize', () => {
         'Unexpected date value: {"date":"123"}'
       );
     });
+
+    test('should handle string numbers', () => {
+      expect(normalizeDate('1696118400000')).toEqual(1696118400000);
+    });
   });
 
   describe('normalizeChallengeType', () => {
diff --git a/api/src/utils/normalize.ts b/api/src/utils/normalize.ts
index b6d1c422f15..bfad634c34e 100644
--- a/api/src/utils/normalize.ts
+++ b/api/src/utils/normalize.ts
@@ -76,9 +76,16 @@ export const normalizeDate = (date?: Prisma.JsonValue): number => {
     typeof date.$date === 'string'
   ) {
     return new Date(date.$date).getTime();
-  } else {
-    throw Error('Unexpected date value: ' + JSON.stringify(date));
+  } else if (typeof date === 'string') {
+    const parsed = Number(date);
+    if (!isNaN(parsed)) {
+      // Number() handles invalid strings e.g. '2023-10-01T00:00:00Z'
+      // parseInt() handles floats
+      return parseInt(String(parsed));
+    }
   }
+
+  throw Error('Unexpected date value: ' + JSON.stringify(date));
 };
 
 /**