diff --git a/lib/sinon/spy.js b/lib/sinon/spy.js
index 3c5f70336..b91a5491b 100644
--- a/lib/sinon/spy.js
+++ b/lib/sinon/spy.js
@@ -152,7 +152,26 @@ function createProxy(func, proxyLength) {
             return p.invoke(func, this, slice(arguments));
         };
     }
-    extend.nonEnum(p, { isSinonProxy: true });
+    extend.nonEnum(p, {
+        isSinonProxy: true,
+
+        called: false,
+        notCalled: true,
+        calledOnce: false,
+        calledTwice: false,
+        calledThrice: false,
+        callCount: 0,
+        firstCall: null,
+        secondCall: null,
+        thirdCall: null,
+        lastCall: null,
+        args: [],
+        returnValues: [],
+        thisValues: [],
+        exceptions: [],
+        callIds: [],
+        errorsWithCallStack: []
+    });
     return p;
 }
 
@@ -172,24 +191,22 @@ var spyApi = {
             throw err;
         }
 
-        extend.nonEnum(this, {
-            called: false,
-            notCalled: true,
-            calledOnce: false,
-            calledTwice: false,
-            calledThrice: false,
-            callCount: 0,
-            firstCall: null,
-            secondCall: null,
-            thirdCall: null,
-            lastCall: null,
-            args: [],
-            returnValues: [],
-            thisValues: [],
-            exceptions: [],
-            callIds: [],
-            errorsWithCallStack: []
-        });
+        this.called = false;
+        this.notCalled = true;
+        this.calledOnce = false;
+        this.calledTwice = false;
+        this.calledThrice = false;
+        this.callCount = 0;
+        this.firstCall = null;
+        this.secondCall = null;
+        this.thirdCall = null;
+        this.lastCall = null;
+        this.args = [];
+        this.returnValues = [];
+        this.thisValues = [];
+        this.exceptions = [];
+        this.callIds = [];
+        this.errorsWithCallStack = [];
 
         if (this.fakes) {
             forEach(this.fakes, function(fake) {
@@ -221,7 +238,7 @@ var spyApi = {
 
         extend.nonEnum(proxy, spy);
         delete proxy.create;
-        extend.nonEnum(proxy, funk);
+        extend(proxy, funk);
 
         proxy.resetHistory();
         proxy.prototype = funk.prototype;
@@ -391,7 +408,7 @@ var spyApi = {
                 return matching;
             }
         } else {
-            this.fakes = [];
+            extend.nonEnum(this, { fakes: [] });
         }
 
         var original = this;
diff --git a/test/spy-test.js b/test/spy-test.js
index dc75661c4..8822512bc 100644
--- a/test/spy-test.js
+++ b/test/spy-test.js
@@ -2851,4 +2851,62 @@ describe("spy", function() {
             }
         });
     });
+
+    describe("non enumerable properties", function() {
+        it("create and call spy apis", function() {
+            var spy = createSpy();
+            assert.equals(Object.keys(spy), []);
+
+            // call spy and verify no enumerable properties are added
+            spy(15);
+            assert.equals(Object.keys(spy), []);
+
+            // it should still work to add properties
+            spy.fooBar = 1;
+            assert.equals(Object.keys(spy), ["fooBar"]);
+
+            // call some spy APIs and verify no enumerable properties are added
+            spy.withArgs(1);
+            // eslint-disable-next-line no-unused-vars
+            var val = spy.called;
+            spy.calledBefore(createSpy());
+            spy.calledAfter(createSpy());
+            spy.calledOn(undefined);
+            spy.calledWith(15);
+            spy.calledWithNew();
+            spy.threw();
+            spy.returned("ret");
+            val = spy.thisValues.length;
+            val = spy.exceptions.length;
+            val = spy.returnValues.length;
+            assert.equals(Object.keys(spy), ["fooBar"]);
+
+            // verify that reset history doesn't change enumerable properties
+            spy.resetHistory();
+            assert.equals(Object.keys(spy), ["fooBar"]);
+        });
+
+        it("create spy from function", function() {
+            var func = function() {
+                throw new Error("aError");
+            };
+            func.aProp = 42;
+            var spy = createSpy.create(func);
+
+            assert.equals(spy.aProp, 42);
+            assert.equals(Object.keys(spy), Object.keys(func));
+            assert.equals(Object.keys(spy), ["aProp"]);
+
+            // eslint-disable-next-line no-restricted-syntax
+            try {
+                spy();
+            } catch (e) {
+                // empty
+            }
+            spy.threw();
+
+            spy.resetHistory();
+            assert.equals(Object.keys(spy), ["aProp"]);
+        });
+    });
 });