diff --git a/Source/cmCacheManager.cxx b/Source/cmCacheManager.cxx
index 8f352b112..d6b84a000 100644
--- a/Source/cmCacheManager.cxx
+++ b/Source/cmCacheManager.cxx
@@ -751,11 +751,7 @@ void cmCacheManager::AddCacheEntry(const std::string& key,
     }
   e.SetProperty("HELPSTRING", helpString? helpString :
                 "(This variable does not exist and should not be used)");
-  if (this->Cache[key].Value == e.Value)
-    {
-    this->CMakeInstance->UnwatchUnusedCli(key);
-    }
-  this->Cache[key] = e;
+  this->CMakeInstance->UnwatchUnusedCli(key);
 }
 
 bool cmCacheManager::CacheIterator::IsAtEnd() const
diff --git a/Source/cmake.cxx b/Source/cmake.cxx
index a83ebd562..976bf441b 100644
--- a/Source/cmake.cxx
+++ b/Source/cmake.cxx
@@ -1236,7 +1236,10 @@ int cmake::HandleDeleteCacheVariables(const std::string& var)
     if(ci.Find(save.key))
       {
       save.type = ci.GetType();
-      save.help = ci.GetProperty("HELPSTRING");
+      if(const char* help = ci.GetProperty("HELPSTRING"))
+        {
+        save.help = help;
+        }
       }
     saved.push_back(save);
     }