diff --git a/catfish/worker/server.py b/catfish/worker/server.py
index 4a4d91a..d1fed1b 100644
--- a/catfish/worker/server.py
+++ b/catfish/worker/server.py
@@ -6,9 +6,11 @@ import signal
 import socket
 import subprocess
 from enum import Enum, auto
+from typing import Optional
 
 import click
 import zmq
+from aiohttp.test_utils import unused_port
 
 import ujson
 from catfish.project import Process, Project
@@ -47,7 +49,9 @@ def write_data(writer, data):
     writer.write(ujson.dumps(data).encode())
 
 
-async def publish_stdout_for(process, ctf_process: Process, project: Project):
+async def publish_stdout_for(
+    process, ctf_process: Process, project: Project, port: Optional[int]
+):
     ctx = zmq.Context()
     sock = ctx.socket(zmq.PUB)
     socket_path = str(BASE_SOCKET_DIR.joinpath(ctf_process.logs_socket))
@@ -63,32 +67,40 @@ async def publish_stdout_for(process, ctf_process: Process, project: Project):
             exit_code = process.returncode
             if exit_code in [-signal.SIGHUP, 0, 1]:
                 # If process gets SIGHUP, or exits cleanly / uncleanly, restart it
-                process = await start_process(project, ctf_process)
+                process = await start_process(project, ctf_process, port)
     finally:
         sock.close()
         ctx.destroy()
         await aio.remove_file(socket_path)
 
 
-async def start_process(project: Project, process: Process):
-    command = shlex.split(process.command)
+async def start_process(project: Project, process: Process, port: Optional[int]):
+    process_env = {
+        **os.environ,
+        **project.get_environment(),
+        "CATFISH_IDENT": process.ident,
+        "CATFISH_WORKER_PROCESS": str(CURRENT_PROCESS.pid),
+    }
+    command = process.command
+    if port is not None:
+        process_env["PORT"] = str(port)
+        command = command.replace("$PORT", str(port))
     return await asyncio.create_subprocess_exec(
-        *command,
+        *shlex.split(command),
         stdout=subprocess.PIPE,
         stderr=subprocess.STDOUT,
-        env={
-            **os.environ,
-            **project.get_environment(),
-            "CATFISH_IDENT": process.ident,
-            "CATFISH_WORKER_PROCESS": str(CURRENT_PROCESS.pid),
-        },
+        env=process_env,
         cwd=project.root
     )
 
 
 async def run_process_command(project: Project, process: Process):
-    proc = await start_process(project, process)
-    asyncio.ensure_future(publish_stdout_for(proc, process, project))
+    if "$PORT" in process.command:
+        port = unused_port()
+    else:
+        port = None
+    proc = await start_process(project, process, port)
+    asyncio.ensure_future(publish_stdout_for(proc, process, project, port))
     return proc
 
 
diff --git a/tests/test_worker/test_server.py b/tests/test_worker/test_server.py
index 157c5c2..1902e3c 100644
--- a/tests/test_worker/test_server.py
+++ b/tests/test_worker/test_server.py
@@ -137,3 +137,41 @@ class ProcessLogsTestCase(BaseWorkerTestCase):
         stdout_iter = read_logs_for_process(self.process)
         for i in range(3):
             self.assertEqual(next(stdout_iter), "Round {}".format(i))
+
+
+class ProcessPortTestCase(BaseWorkerTestCase):
+    def setUp(self):
+        super().setUp()
+        self.project = Project(self.EXAMPLE_DIR)
+        self.process = self.project.get_process("web")
+
+    def test_assigns_port(self):
+        response = send_to_server(
+            PayloadType.PROCESS,
+            {"path": str(self.project.root), "process": str(self.process.name)},
+        )
+        process = psutil.Process(response["pid"])
+        self.assertIn("PORT", process.environ())
+        self.assertEqual(self.process.port, process.environ()["PORT"])
+
+    def test_doesnt_assign_port(self):
+        response = send_to_server(
+            PayloadType.PROCESS, {"path": str(self.project.root), "process": "bg"}
+        )
+        process = psutil.Process(response["pid"])
+        self.assertNotIn("PORT", process.environ())
+        self.assertIsNone(self.process.port)
+
+    def test_keeps_port_on_restart(self):
+        response = send_to_server(
+            PayloadType.PROCESS,
+            {"path": str(self.project.root), "process": str(self.process.name)},
+        )
+        initial_pid = response["pid"]
+        initial_process = psutil.Process(initial_pid)
+        port = initial_process.environ()["PORT"]
+        psutil.Process(initial_pid).send_signal(signal.SIGHUP)
+        wait_for_process_terminate(initial_pid)
+        time.sleep(2)
+        new_process = get_running_process_for(self.process)
+        self.assertEqual(new_process.environ()["PORT"], port)