diff --git a/mustache.js b/mustache.js
index 602d7b3..67c222d 100644
--- a/mustache.js
+++ b/mustache.js
@@ -356,7 +356,7 @@
     var cache = this.cache;
 
     var value;
-    if (name in cache) {
+    if (cache.hasOwnProperty(name)) {
       value = cache[name];
     } else {
       var context = this, names, index, lookupHit = false;
diff --git a/test/_files/avoids_obj_prototype_in_view_cache.js b/test/_files/avoids_obj_prototype_in_view_cache.js
new file mode 100644
index 0000000..2ab58cd
--- /dev/null
+++ b/test/_files/avoids_obj_prototype_in_view_cache.js
@@ -0,0 +1,4 @@
+({
+  valueOf: 'Avoids methods',
+  watch: 'in Object.prototype'
+})
diff --git a/test/_files/avoids_obj_prototype_in_view_cache.mustache b/test/_files/avoids_obj_prototype_in_view_cache.mustache
new file mode 100644
index 0000000..f6e469b
--- /dev/null
+++ b/test/_files/avoids_obj_prototype_in_view_cache.mustache
@@ -0,0 +1 @@
+{{valueOf}} {{watch}}
\ No newline at end of file
diff --git a/test/_files/avoids_obj_prototype_in_view_cache.txt b/test/_files/avoids_obj_prototype_in_view_cache.txt
new file mode 100644
index 0000000..2621d99
--- /dev/null
+++ b/test/_files/avoids_obj_prototype_in_view_cache.txt
@@ -0,0 +1 @@
+Avoids methods in Object.prototype
\ No newline at end of file