diff --git a/CMakeLists.txt b/CMakeLists.txt
index a5cd2ee..1bc5852 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,7 +18,7 @@ endif()
 FetchContent_Declare(
     sqlite_zstd_vfs
     GIT_REPOSITORY  https://github.com/mlin/sqlite_zstd_vfs.git
-    GIT_TAG         25e962e
+    GIT_TAG         2e9c7db
 )
 FetchContent_MakeAvailable(sqlite_zstd_vfs)
 FetchContent_MakeAvailable(sqlitecpp)
diff --git a/docs/guide_db.md b/docs/guide_db.md
index e8beed7..7b8abea 100644
--- a/docs/guide_db.md
+++ b/docs/guide_db.md
@@ -205,7 +205,7 @@ The **GenomicSQLite Open** routine and the `genomicsqlite` shell also accept htt
 Under the hood, the extension uses [libcurl](https://curl.se/libcurl/) to send web requests for necessary portions of the database file as queries proceed, with adaptive batching & prefetching to balance the number and size of these requests. This works well for point lookups and queries that scan largely-contiguous slices of tables and indexes (and a modest number thereof). It's less suitable for big multi-way joins and other aggressively random access patterns; in such cases, it'd be better to download the database file upfront to open locally.
 
 * Reading large databases over the web, budget an additional ~600MiB of memory for HTTP prefetch buffers.
-* The HTTP driver writes log messages to standard error when requests fail or had to be retried, which can be disabled by setting configuration web_log = 0 or environment SQLITE_WEB_LOG=0; or increased up to 5 to log every request and other details.
+* The HTTP driver writes log messages to standard error when requests fail or had to be retried, which can be disabled by setting configuration vfs_log = 0 or environment SQLITE_VFS_LOG=0; or increased up to 5 for extensive debug logging.
 * To disable TLS certificate and hostname verification, set web_insecure = true in the GenomicSQLite configuration, or SQLITE_WEB_INSECURE=1 in the environment.
 * The above-described `genomicsqlite DB_FILENAME --compact` optimizes a database for web access by making the request pattern more contiguous.
 
diff --git a/src/genomicsqlite.cc b/src/genomicsqlite.cc
index 350b985..45e1248 100644
--- a/src/genomicsqlite.cc
+++ b/src/genomicsqlite.cc
@@ -68,7 +68,7 @@ std::string GenomicSQLiteDefaultConfigJSON() {
     "zstd_level": 6,
     "inner_page_KiB": 16,
     "outer_page_KiB": 32,
-    "web_log": 2,
+    "vfs_log": -1,
     "web_insecure": false,
     "web_dbi_url": "",
     "web_nodbi": false,
@@ -173,9 +173,11 @@ string GenomicSQLiteURI(const string &dbfile, const string &config_json = "") {
     bool web = dbfile.substr(0, 5) == "http:" || dbfile.substr(0, 6) == "https:";
     ostringstream uri;
     uri << "file:" << (web ? "/__web__" : SQLiteNested::urlencode(dbfile, true)) << "?vfs=zstd";
+    if (cfg.GetInt("$.vfs_log") >= 0) {
+        uri << "&vfs_log=" << cfg.GetInt("$.vfs_log");
+    }
     if (web) {
-        uri << "&mode=ro&immutable=1&web_url=" << SQLiteNested::urlencode(dbfile)
-            << "&web_log=" << cfg.GetInt("$.web_log");
+        uri << "&mode=ro&immutable=1&web_url=" << SQLiteNested::urlencode(dbfile);
         if (cfg.GetBool("$.web_insecure")) {
             uri << "&web_insecure=1";
         }