diff --git a/Mortein/Mqtt/Extensions/ServiceCollectionExtension.cs b/Mortein/Mqtt/Extensions/ServiceCollectionExtension.cs
index 81d7194..a85592e 100644
--- a/Mortein/Mqtt/Extensions/ServiceCollectionExtension.cs
+++ b/Mortein/Mqtt/Extensions/ServiceCollectionExtension.cs
@@ -11,7 +11,10 @@ namespace Mortein.Mqtt.Extensions;
 public static class ServiceCollectionExtension
 {
     // TODO: read from somewhere other than the local filesystem.
-    private static readonly X509Certificate2 certificate = new("/workspaces/api/api.pfx");
+    private static readonly X509Certificate2 certificate =
+        Environment.GetEnvironmentVariable("CERTIFICATE") != null ?
+            new(Environment.GetEnvironmentVariable("CERTIFICATE")!) : // prod
+            new("/workspaces/api/api.pfx");                           // dev
 
     /// <summary>
     /// Registers a hosted MQTT client as a service in the <see cref="IServiceCollection" />.