diff --git a/Cargo.lock b/Cargo.lock
index 1ed64bb..4cdb574 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -246,6 +246,12 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "acbf1af155f9b9ef647e42cdc158db4b64a1b61f743629225fde6f3e0be2a7c7"
 
+[[package]]
+name = "const_fn"
+version = "0.4.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fbdcdcb6d86f71c5e97409ad45898af11cbc995b4ee8112d59095a28d376c935"
+
 [[package]]
 name = "cookie"
 version = "0.18.0"
@@ -297,6 +303,7 @@ dependencies = [
  "tokio",
  "tokio-tungstenite",
  "toss",
+ "tz-rs",
  "unicode-segmentation",
  "unicode-width",
  "vault",
@@ -1507,6 +1514,15 @@ version = "1.17.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "42ff0bf0c66b8238c6f3b578df37d0b7848e55df8577b3f74f92a69acceeb825"
 
+[[package]]
+name = "tz-rs"
+version = "0.6.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "33851b15c848fad2cf4b105c6bb66eb9512b6f6c44a4b13f57c53c73c707e2b4"
+dependencies = [
+ "const_fn",
+]
+
 [[package]]
 name = "unicode-bidi"
 version = "0.3.14"
diff --git a/cove/Cargo.toml b/cove/Cargo.toml
index 9687080..b764a4a 100644
--- a/cove/Cargo.toml
+++ b/cove/Cargo.toml
@@ -24,6 +24,7 @@ open = "5.0.1"
 rusqlite = { version = "0.30.0", features = ["bundled", "time"] }
 serde_json = "1.0.108"
 tokio = { version = "1.35.1", features = ["full"] }
+tz-rs = "0.6.14"
 unicode-segmentation = "1.10.1"
 unicode-width = "0.1.11"
 
diff --git a/cove/src/main.rs b/cove/src/main.rs
index e5eeb5c..0308604 100644
--- a/cove/src/main.rs
+++ b/cove/src/main.rs
@@ -129,14 +129,18 @@ fn update_config_with_args(config: &mut Config, args: &Args) {
     config.offline |= args.offline;
 }
 
-fn open_vault(config: &Config, dirs: &ProjectDirs) -> rusqlite::Result<Vault> {
-    if config.ephemeral {
-        vault::launch_in_memory()
+fn open_vault(config: &Config, dirs: &ProjectDirs) -> anyhow::Result<Vault> {
+    let time_zone = util::load_time_zone(config.time_zone_ref())?;
+
+    let vault = if config.ephemeral {
+        vault::launch_in_memory(time_zone)?
     } else {
         let data_dir = data_dir(config, dirs);
         eprintln!("Data dir:    {}", data_dir.to_string_lossy());
-        vault::launch(&data_dir.join("vault.db"))
-    }
+        vault::launch(&data_dir.join("vault.db"), time_zone)?
+    };
+
+    Ok(vault)
 }
 
 #[tokio::main]
diff --git a/cove/src/util.rs b/cove/src/util.rs
index b6e7c97..67c0e68 100644
--- a/cove/src/util.rs
+++ b/cove/src/util.rs
@@ -1,4 +1,7 @@
 use std::convert::Infallible;
+use std::env;
+
+use tz::{TimeZone, TzError};
 
 pub trait InfallibleExt {
     type Inner;
@@ -13,3 +16,22 @@ impl<T> InfallibleExt for Result<T, Infallible> {
         self.expect("infallible")
     }
 }
+
+/// Load a [`TimeZone`] specified by a string, or by the `TZ` environment
+/// variable if no string is provided.
+///
+/// If a string is provided, it is interpreted in the same format that the `TZ`
+/// environment variable uses.
+///
+/// If no string and no `TZ` environment variable could be found, the system
+/// local time is used.
+pub fn load_time_zone(tz_string: Option<&str>) -> Result<TimeZone, TzError> {
+    let env_tz = env::var("TZ").ok();
+    let tz_string = tz_string.or(env_tz.as_ref().map(|s| s as &str));
+
+    match &tz_string {
+        // At the moment, TimeZone::from_posix_tz does not support "localtime" on windows, but other time zon
+        Some("localtime") | None => TimeZone::local(),
+        Some(tz_string) => TimeZone::from_posix_tz(tz_string),
+    }
+}
diff --git a/cove/src/vault.rs b/cove/src/vault.rs
index 6861901..250456d 100644
--- a/cove/src/vault.rs
+++ b/cove/src/vault.rs
@@ -6,6 +6,7 @@ use std::fs;
 use std::path::Path;
 
 use rusqlite::Connection;
+use tz::TimeZone;
 use vault::tokio::TokioVault;
 use vault::Action;
 
@@ -14,6 +15,7 @@ pub use self::euph::{EuphRoomVault, EuphVault, RoomIdentifier};
 #[derive(Debug, Clone)]
 pub struct Vault {
     tokio_vault: TokioVault,
+    time_zone: TimeZone,
     ephemeral: bool,
 }
 
@@ -46,18 +48,23 @@ impl Vault {
     }
 }
 
-fn launch_from_connection(conn: Connection, ephemeral: bool) -> rusqlite::Result<Vault> {
+fn launch_from_connection(
+    conn: Connection,
+    time_zone: TimeZone,
+    ephemeral: bool,
+) -> rusqlite::Result<Vault> {
     conn.pragma_update(None, "foreign_keys", true)?;
     conn.pragma_update(None, "trusted_schema", false)?;
 
     let tokio_vault = TokioVault::launch_and_prepare(conn, &migrate::MIGRATIONS, prepare::prepare)?;
     Ok(Vault {
         tokio_vault,
+        time_zone,
         ephemeral,
     })
 }
 
-pub fn launch(path: &Path) -> rusqlite::Result<Vault> {
+pub fn launch(path: &Path, time_zone: TimeZone) -> rusqlite::Result<Vault> {
     // If this fails, rusqlite will complain about not being able to open the db
     // file, which saves me from adding a separate vault error type.
     let _ = fs::create_dir_all(path.parent().expect("path to file"));
@@ -72,10 +79,10 @@ pub fn launch(path: &Path) -> rusqlite::Result<Vault> {
     conn.pragma_update(None, "locking_mode", "exclusive")?;
     conn.pragma_update(None, "journal_mode", "wal")?;
 
-    launch_from_connection(conn, false)
+    launch_from_connection(conn, time_zone, false)
 }
 
-pub fn launch_in_memory() -> rusqlite::Result<Vault> {
+pub fn launch_in_memory(time_zone: TimeZone) -> rusqlite::Result<Vault> {
     let conn = Connection::open_in_memory()?;
-    launch_from_connection(conn, true)
+    launch_from_connection(conn, time_zone, true)
 }