diff --git a/README.md b/README.md
index 0c299d3..012eba9 100644
--- a/README.md
+++ b/README.md
@@ -175,7 +175,7 @@ gastown-gui help
 | Variable | Description | Default |
 |----------|-------------|---------|
 | `GASTOWN_PORT` | Server port | 7667 |
-| `HOST` | Server host | 127.0.0.1 |
+| `GASTOWN_HOST` | Server host | 127.0.0.1 |
 | `GT_ROOT` | Gas Town root directory | ~/gt |
 | `GT_BIN` | Override `gt` executable path | auto-detect (`PATH`, `/opt/homebrew/bin/gt`, `/usr/local/bin/gt`) |
 | `BD_BIN` | Override `bd` executable path | auto-detect (`PATH`, `/opt/homebrew/bin/bd`, `/usr/local/bin/bd`) |
diff --git a/bin/cli.js b/bin/cli.js
index a2ba8a4..609562e 100755
--- a/bin/cli.js
+++ b/bin/cli.js
@@ -15,7 +15,7 @@
  *
  * Options:
  *   --port, -p    Port to run on (default: 7667)
- *   --host, -h    Host to bind to (default: 127.0.0.1)
+ *   --host, -h    Host to bind to (default: 127.0.0.1, or GASTOWN_HOST env var)
  *   --open, -o    Open browser after starting
  *   --dev         Enable development mode (auto-reload)
  */
@@ -45,7 +45,7 @@ if (args.includes('--version') || args.includes('-v')) {
 const command = args.find(a => !a.startsWith('-')) || 'start';
 const options = {
   port: getOption(['--port', '-p']) || process.env.GASTOWN_PORT || '7667',
-  host: getOption(['--host', '-h']) || process.env.HOST || '127.0.0.1',
+  host: getOption(['--host', '-h']) || process.env.GASTOWN_HOST || '127.0.0.1',
   open: hasFlag(['--open', '-o']),
   dev: hasFlag(['--dev']),
 };
@@ -79,13 +79,13 @@ Commands:
 
 Options:
   --port, -p <port>   Port to run on (default: 7667, or GASTOWN_PORT env var)
-  --host, -h <host>   Host to bind to (default: 127.0.0.1, or HOST env var)
+  --host, -h <host>   Host to bind to (default: 127.0.0.1, or GASTOWN_HOST env var)
   --open, -o          Open browser after starting
   --dev               Enable development mode
 
 Environment Variables:
   GASTOWN_PORT Server port (default: 7667)
-  HOST         Server host (default: 127.0.0.1)
+  GASTOWN_HOST Server host (default: 127.0.0.1)
   GT_ROOT      Gas Town root directory (default: ~/gt)
 
 Examples:
@@ -209,7 +209,7 @@ function startServer() {
   const env = {
     ...process.env,
     GASTOWN_PORT: options.port,
-    HOST: options.host,
+    GASTOWN_HOST: options.host,
   };
 
   const serverPath = path.join(packageRoot, 'server.js');
diff --git a/server.js b/server.js
index 53737b8..90643c9 100644
--- a/server.js
+++ b/server.js
@@ -63,7 +63,11 @@ const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
 
 const PORT = process.env.GASTOWN_PORT || 7667;
-const HOST = process.env.HOST || '127.0.0.1';
+// Use GASTOWN_HOST (not the bare HOST env var, which collides with the
+// compiler-toolchain convention, e.g. HOST=arm64-apple-darwin* set by
+// conda/clang cross-compile shells — that would make the server try to bind
+// to an unresolvable hostname and crash with getaddrinfo ENOTFOUND).
+const HOST = process.env.GASTOWN_HOST || '127.0.0.1';
 const HOME = process.env.HOME || os.homedir();
 const GT_ROOT = process.env.GT_ROOT || path.join(HOME, 'gt');
 const GT_EXECUTABLE = resolveExecutable({
diff --git a/test/integration/cli-compatibility.test.js b/test/integration/cli-compatibility.test.js
index 5afff58..114ad1b 100644
--- a/test/integration/cli-compatibility.test.js
+++ b/test/integration/cli-compatibility.test.js
@@ -63,7 +63,7 @@ async function startRealServerFixture({ gtScript, bdScript, ghScript }) {
     env: {
       ...process.env,
       GASTOWN_PORT: String(port),
-      HOST: '127.0.0.1',
+      GASTOWN_HOST: '127.0.0.1',
       GT_ROOT: gtRoot,
       PATH: `${binDir}:${process.env.PATH}`,
       GT_CALL_LOG: gtCallLog,
diff --git a/test/integration/cli-executable-resolution.test.js b/test/integration/cli-executable-resolution.test.js
index 43f25c3..96bee11 100644
--- a/test/integration/cli-executable-resolution.test.js
+++ b/test/integration/cli-executable-resolution.test.js
@@ -90,7 +90,7 @@ async function startFixture({ gtScript, bdScript, ghScript, env = {} }) {
     env: {
       ...process.env,
       GASTOWN_PORT: String(port),
-      HOST: '127.0.0.1',
+      GASTOWN_HOST: '127.0.0.1',
       GT_ROOT: gtRoot,
       PATH: binDir,
       ...env,
diff --git a/test/integration/realtime-cache-invalidation.test.js b/test/integration/realtime-cache-invalidation.test.js
index 7f3fab6..bf84e2c 100644
--- a/test/integration/realtime-cache-invalidation.test.js
+++ b/test/integration/realtime-cache-invalidation.test.js
@@ -187,7 +187,7 @@ exit 1
       env: {
         ...process.env,
         GASTOWN_PORT: String(port),
-        HOST: '127.0.0.1',
+        GASTOWN_HOST: '127.0.0.1',
         GT_ROOT: gtRoot,
         PATH: `${binDir}:${process.env.PATH}`,
       },
diff --git a/test/integration/rig-parsing-fallback.test.js b/test/integration/rig-parsing-fallback.test.js
index f34c077..a15b75c 100644
--- a/test/integration/rig-parsing-fallback.test.js
+++ b/test/integration/rig-parsing-fallback.test.js
@@ -108,7 +108,7 @@ exit 1
       env: {
         ...process.env,
         GASTOWN_PORT: String(port),
-        HOST: '127.0.0.1',
+        GASTOWN_HOST: '127.0.0.1',
         GT_ROOT: gtRoot,
         PATH: `${binDir}:${process.env.PATH}`,
       },