diff --git a/spec/core/SpyRegistrySpec.js b/spec/core/SpyRegistrySpec.js
index 0511e2a8..4ce31ddd 100644
--- a/spec/core/SpyRegistrySpec.js
+++ b/spec/core/SpyRegistrySpec.js
@@ -89,5 +89,22 @@ describe("SpyRegistry", function() {
 
       expect(subject.spiedFunc).toBe(originalFunction);
     });
+
+    it("does not add a property that the spied-upon object didn't originally have", function() {
+      var spies = [],
+        spyRegistry = new jasmineUnderTest.SpyRegistry({currentSpies: function() { return spies; }}),
+        originalFunction = function() {},
+        subjectParent = {spiedFunc: originalFunction};
+
+      var subject = Object.create(subjectParent);
+
+      expect(subject.hasOwnProperty('spiedFunc')).toBe(false);
+
+      spyRegistry.spyOn(subject, 'spiedFunc');
+      spyRegistry.clearSpies();
+
+      expect(subject.hasOwnProperty('spiedFunc')).toBe(false);
+      expect(subject.spiedFunc).toBe(originalFunction);
+    })
   });
 });
diff --git a/src/core/SpyRegistry.js b/src/core/SpyRegistry.js
index 25c9b343..7215ca67 100644
--- a/src/core/SpyRegistry.js
+++ b/src/core/SpyRegistry.js
@@ -33,25 +33,34 @@ getJasmineRequireObj().SpyRegistry = function(j$) {
         throw new Error(methodName + ' is not declared writable or has no setter');
       }
 
-      var spy = j$.createSpy(methodName, obj[methodName]);
+      var originalMethod = obj[methodName],
+        spiedMethod = j$.createSpy(methodName, originalMethod),
+        restoreStrategy;
+
+      if (Object.prototype.hasOwnProperty.call(obj, methodName)) {
+        restoreStrategy = function() {
+          obj[methodName] = originalMethod;
+        };
+      } else {
+        restoreStrategy = function() {
+          delete obj[methodName];
+        };
+      }
 
       currentSpies().push({
-        spy: spy,
-        baseObj: obj,
-        methodName: methodName,
-        originalValue: obj[methodName]
+        restoreObjectToOriginalState: restoreStrategy
       });
 
-      obj[methodName] = spy;
+      obj[methodName] = spiedMethod;
 
-      return spy;
+      return spiedMethod;
     };
 
     this.clearSpies = function() {
       var spies = currentSpies();
       for (var i = 0; i < spies.length; i++) {
         var spyEntry = spies[i];
-        spyEntry.baseObj[spyEntry.methodName] = spyEntry.originalValue;
+        spyEntry.restoreObjectToOriginalState();
       }
     };
   }