diff --git a/CHANGELOG.md b/CHANGELOG.md
index c25e3d3..96f4115 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 
+## [Unreleased]
+
+### Added
+- configuration option `pass_environment` which specifies a list of env var names to be passed from ra-multiplex client proxy to the spawned language server (rust-analyzer)
+
+
 ## [v0.2.4] - 2024-05-15
 
 ### Fixed
diff --git a/defaults.toml b/defaults.toml
index e2230ed..e715602 100644
--- a/defaults.toml
+++ b/defaults.toml
@@ -3,3 +3,4 @@ gc_interval = 10
 listen = ["127.0.0.1", 27631]
 connect = ["127.0.0.1", 27631]
 log_filters = "info"
+pass_environment = []
diff --git a/src/client.rs b/src/client.rs
index 186f850..3b5d1e2 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -1,3 +1,4 @@
+use std::collections::BTreeMap;
 use std::io::ErrorKind;
 use std::sync::Arc;
 
@@ -62,11 +63,16 @@ pub async fn process(
 
     debug!(?options, "lspmux initialization");
     match options.method {
-        ext::Request::Connect { server, args, cwd } => {
+        ext::Request::Connect {
+            server,
+            args,
+            env,
+            cwd,
+        } => {
             connect(
                 port,
                 instance_map,
-                (server, args, cwd),
+                (server, args, env, cwd),
                 req,
                 init_params,
                 reader,
@@ -164,7 +170,12 @@ async fn reload(
 async fn connect(
     port: u16,
     instance_map: Arc<Mutex<InstanceMap>>,
-    (server, args, cwd): (String, Vec<String>, Option<String>),
+    (server, args, env, cwd): (
+        String,
+        Vec<String>,
+        BTreeMap<String, String>,
+        Option<String>,
+    ),
     req: Request,
     init_params: InitializeParams,
     mut reader: LspReader<BufReader<OwnedReadHalf>>,
@@ -178,6 +189,7 @@ async fn connect(
     let key = InstanceKey {
         server,
         args,
+        env,
         workspace_root,
     };
     let instance = instance::get_or_spawn(instance_map, key, init_params).await?;
diff --git a/src/config.rs b/src/config.rs
index bcd2e9c..2bb9f93 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1,5 +1,6 @@
 use std::fs;
 use std::net::{IpAddr, Ipv4Addr};
+use std::collections::BTreeSet;
 
 use anyhow::{Context, Result};
 use directories::ProjectDirs;
@@ -32,6 +33,10 @@ mod default {
     pub fn log_filters() -> String {
         "info".to_owned()
     }
+
+    pub fn pass_environment() -> BTreeSet<String> {
+        BTreeSet::new()
+    }
 }
 
 mod de {
@@ -96,6 +101,9 @@ pub struct Config {
 
     #[serde(default = "default::log_filters")]
     pub log_filters: String,
+
+    #[serde(default = "default::pass_environment")]
+    pub pass_environment: BTreeSet<String>,
 }
 
 #[cfg(test)]
@@ -121,6 +129,7 @@ impl Default for Config {
             listen: default::listen(),
             connect: default::connect(),
             log_filters: default::log_filters(),
+            pass_environment: default::pass_environment(),
         }
     }
 }
diff --git a/src/ext.rs b/src/ext.rs
index 0601761..330de3f 100644
--- a/src/ext.rs
+++ b/src/ext.rs
@@ -86,6 +86,12 @@ pub async fn status(config: &Config, json: bool) -> Result<()> {
         println!("- Instance");
         println!("  pid: {}", instance.pid);
         println!("  server: {:?} {:?}", instance.server, instance.args);
+        if !instance.env.is_empty() {
+            println!("  server env:");
+            for (key, val) in instance.env {
+                println!("    {key} = {val}");
+            }
+        }
         println!("  path: {:?}", instance.workspace_root);
         let now = time::OffsetDateTime::now_utc().unix_timestamp();
         println!("  last used: {}s ago", now - instance.last_used);
diff --git a/src/instance.rs b/src/instance.rs
index b2de494..24288dd 100644
--- a/src/instance.rs
+++ b/src/instance.rs
@@ -1,5 +1,5 @@
 use std::collections::hash_map::Entry;
-use std::collections::{HashMap, HashSet};
+use std::collections::{BTreeMap, HashMap, HashSet};
 use std::io::ErrorKind;
 use std::ops::Deref;
 use std::path::Path;
@@ -31,6 +31,7 @@ use crate::lsp::{self, ext};
 pub struct InstanceKey {
     pub server: String,
     pub args: Vec<String>,
+    pub env: BTreeMap<String, String>,
     pub workspace_root: String,
 }
 
@@ -310,6 +311,7 @@ impl Instance {
             pid: self.pid,
             server: self.key.server.clone(),
             args: self.key.args.clone(),
+            env: self.key.env.clone(),
             workspace_root: self.key.workspace_root.clone(),
             last_used: self.last_used.load(Ordering::Relaxed),
             clients,
@@ -422,6 +424,7 @@ async fn spawn(
 ) -> Result<Arc<Instance>> {
     let mut child = Command::new(&key.server)
         .args(&key.args)
+        .envs(&key.env)
         .current_dir(&key.workspace_root)
         .stdin(Stdio::piped())
         .stdout(Stdio::piped())
diff --git a/src/lsp/ext.rs b/src/lsp/ext.rs
index 2e4a8fe..fd05bc6 100644
--- a/src/lsp/ext.rs
+++ b/src/lsp/ext.rs
@@ -1,5 +1,6 @@
 //! LSP-mux (ra-multiplex) specific protocol extensions
 
+use std::collections::BTreeMap;
 use std::str::FromStr;
 
 use anyhow::{bail, Context, Result};
@@ -123,10 +124,15 @@ pub enum Request {
         server: String,
 
         /// Arguments which will be passed to the language server, defaults to an
-        /// empty list if omited.
+        /// empty list if omitted.
         #[serde(default = "Vec::new")]
         args: Vec<String>,
 
+        /// Environment variables which will be set for the language server,
+        /// defaults to an empty set if omitted.
+        #[serde(default = "BTreeMap::new", skip_serializing_if = "BTreeMap::is_empty")]
+        env: BTreeMap<String, String>,
+
         /// Current working directory of the proxy command. This is only used as
         /// fallback if the client doesn't provide any workspace root.
         #[serde(skip_serializing_if = "Option::is_none")]
@@ -159,6 +165,7 @@ pub struct Instance {
     pub pid: u32,
     pub server: String,
     pub args: Vec<String>,
+    pub env: BTreeMap<String, String>,
     pub workspace_root: String,
     pub registered_dyn_capabilities: Vec<String>,
     pub last_used: i64,
diff --git a/src/proxy.rs b/src/proxy.rs
index fbc26a8..a1dc9dc 100644
--- a/src/proxy.rs
+++ b/src/proxy.rs
@@ -1,3 +1,4 @@
+use std::collections::BTreeMap;
 use std::env;
 use std::pin::Pin;
 use std::task::{Context, Poll};
@@ -58,6 +59,13 @@ pub async fn run(config: &Config, server: String, args: Vec<String>) -> Result<(
         .ok()
         .and_then(|path| path.to_str().map(String::from));
 
+    let mut env = BTreeMap::new();
+    for key in &config.pass_environment {
+       if let Ok(val) = std::env::var(key) {
+           env.insert(key.clone(), val);
+       }
+    }
+
     let mut stream = TcpStream::connect(config.connect)
         .await
         .context("connect")?;
@@ -79,7 +87,7 @@ pub async fn run(config: &Config, server: String, args: Vec<String>) -> Result<(
         .lsp_mux
         .get_or_insert_with(|| LspMuxOptions {
             version: LspMuxOptions::PROTOCOL_VERSION.to_owned(),
-            method: Request::Connect { server, args, cwd },
+            method: Request::Connect { server, args, env, cwd },
         });
     req.params = serde_json::to_value(params).expect("BUG: invalid data");