diff --git a/config/runtime.exs b/config/runtime.exs
index 287bded..910011c 100644
--- a/config/runtime.exs
+++ b/config/runtime.exs
@@ -1,13 +1,17 @@
 import Config
 
-if port = System.get_env("SYMBIONT_PORT") do
-  config :symbiont, port: String.to_integer(port)
-end
+# Skip env-based overrides in test mode so that test.exs values (port: 0,
+# telepathy: disabled) are not stomped by shell env vars from the live service.
+if config_env() != :test do
+  if port = System.get_env("SYMBIONT_PORT") do
+    config :symbiont, port: String.to_integer(port)
+  end
 
-if data_dir = System.get_env("SYMBIONT_DATA_DIR") do
-  config :symbiont, data_dir: data_dir
-end
+  if data_dir = System.get_env("SYMBIONT_DATA_DIR") do
+    config :symbiont, data_dir: data_dir
+  end
 
-if System.get_env("TELEPATHY_ENABLED") == "false" do
-  config :symbiont, :telepathy, enabled: false
+  if System.get_env("TELEPATHY_ENABLED") == "false" do
+    config :symbiont, :telepathy, enabled: false
+  end
 end