diff --git a/lib/service/interface.js b/lib/service/interface.js
index d693e85..476a9b4 100644
--- a/lib/service/interface.js
+++ b/lib/service/interface.js
@@ -79,13 +79,18 @@ function property (options) {
     throw new Error('missing signature for property');
   }
   options.signatureTree = parseSignature(options.signature);
-  return function (descriptor) {
-    options.name = options.name || descriptor.key;
-    assertMemberNameValid(options.name);
-    descriptor.finisher = function (klass) {
-      klass.prototype.$properties = klass.prototype.$properties || [];
-      klass.prototype.$properties[descriptor.key] = options;
-    };
+  return function (target, key, descriptor) {
+    const name = options.name || key;
+    assertMemberNameValid(name);
+    options.name = name;
+
+    let properties = target.$properties;
+    if (properties === undefined) {
+      properties = {};
+      target.$properties = properties;
+    }
+    properties[key] = options;
+
     return descriptor;
   };
 }
@@ -152,14 +157,20 @@ function method (options) {
   options.outSignature = options.outSignature || '';
   options.inSignatureTree = parseSignature(options.inSignature);
   options.outSignatureTree = parseSignature(options.outSignature);
-  return function (descriptor) {
-    options.name = options.name || descriptor.key;
-    assertMemberNameValid(options.name);
-    options.fn = descriptor.descriptor.value;
-    descriptor.finisher = function (klass) {
-      klass.prototype.$methods = klass.prototype.$methods || [];
-      klass.prototype.$methods[descriptor.key] = options;
-    };
+
+  return function (target, key, descriptor) {
+    const name = options.name || key;
+    assertMemberNameValid(name);
+    options.name = name;
+    options.fn = descriptor.value;
+
+    let methods = target.$methods;
+    if (methods === undefined) {
+      methods = {};
+      target.$methods = methods;
+    }
+    methods[key] = options;
+
     return descriptor;
   };
 }
@@ -204,21 +215,28 @@ function signal (options) {
   // https://stackoverflow.com/questions/1007981/how-to-get-function-parameter-names-values-dynamically
   options.signature = options.signature || '';
   options.signatureTree = parseSignature(options.signature);
-  return function (descriptor) {
-    options.name = options.name || descriptor.key;
-    assertMemberNameValid(options.name);
-    options.fn = descriptor.descriptor.value;
-    descriptor.descriptor.value = function () {
+
+  return function (target, key, descriptor) {
+    const name = options.name || key;
+    assertMemberNameValid(name);
+    options.name = name;
+    options.fn = descriptor.value;
+
+    descriptor.value = function () {
       if (options.disabled) {
         throw new Error('tried to call a disabled signal');
       }
       const result = options.fn.apply(this, arguments);
       this.$emitter.emit('signal', options, result);
     };
-    descriptor.finisher = function (klass) {
-      klass.prototype.$signals = klass.prototype.$signals || [];
-      klass.prototype.$signals[descriptor.key] = options;
-    };
+
+    let signals = target.$signals;
+    if (signals === undefined) {
+      signals = {};
+      target.$signals = signals;
+    }
+    signals[key] = options;
+
     return descriptor;
   };
 }