diff --git a/src/main/java/com/google/genai/AsyncFileSearchStores.java b/src/main/java/com/google/genai/AsyncFileSearchStores.java
index 315caabf68f..3bd43debf4c 100644
--- a/src/main/java/com/google/genai/AsyncFileSearchStores.java
+++ b/src/main/java/com/google/genai/AsyncFileSearchStores.java
@@ -189,9 +189,12 @@ private CompletableFuture<String> getUploadUrl(
     HttpOptions httpOptions =
         UploadClient.buildResumableUploadHttpOptions(
             userHttpOptions, mimeTypeToUse, fileName, size);
+    if (config == null) {
+      config = UploadToFileSearchStoreConfig.builder().build();
+    }
     return privateUploadToFileSearchStore(
             fileSearchStoreName,
-            UploadToFileSearchStoreConfig.builder()
+            config.toBuilder()
                 .httpOptions(httpOptions)
                 .shouldReturnHttpResponse(true)
                 .build())
diff --git a/src/main/java/com/google/genai/FileSearchStores.java b/src/main/java/com/google/genai/FileSearchStores.java
index 96d9964e387..a8619fd172c 100644
--- a/src/main/java/com/google/genai/FileSearchStores.java
+++ b/src/main/java/com/google/genai/FileSearchStores.java
@@ -929,10 +929,13 @@ private String getUploadUrl(
     HttpOptions httpOptions =
         UploadClient.buildResumableUploadHttpOptions(
             userHttpOptions, mimeTypeToUse, fileName, size);
+    if (config == null) {
+      config = UploadToFileSearchStoreConfig.builder().build();
+    }
     UploadToFileSearchStoreResumableResponse response =
         privateUploadToFileSearchStore(
             fileSearchStoreName,
-            UploadToFileSearchStoreConfig.builder()
+            config.toBuilder()
                 .httpOptions(httpOptions)
                 .shouldReturnHttpResponse(true)
                 .build());