diff --git a/test/support/src/vfs_helpers.cc b/test/support/src/vfs_helpers.cc
index e488ac5833e..996a6c070ef 100644
--- a/test/support/src/vfs_helpers.cc
+++ b/test/support/src/vfs_helpers.cc
@@ -176,6 +176,12 @@ Status SupportedFsS3::prepare_config(
       tiledb_config_set(config, "ssl.verify", "false", &error) == TILEDB_OK);
   REQUIRE(error == nullptr);
 #endif
+  if (is_rest()) {
+    REQUIRE(
+        tiledb_config_set(
+            config, "rest.server_serialization_format", "JSON", &error) ==
+        TILEDB_OK);
+  }
 
   return Status::Ok();
 }