diff --git a/src/Storage.cpp b/src/Storage.cpp
index ba52eac3ae..47a467eecd 100644
--- a/src/Storage.cpp
+++ b/src/Storage.cpp
@@ -140,7 +140,7 @@ void Storage::SavePersistent(std::ostream& os) const {
       }
       case NT_STRING_ARRAY: {
         bool first = true;
-        for (auto elem : v.GetStringArray()) {
+        for (auto& elem : v.GetStringArray()) {
           if (!first) {
             os << ',';
             first = false;
diff --git a/src/Value.h b/src/Value.h
index d04c0978b2..b8b2049d9e 100644
--- a/src/Value.h
+++ b/src/Value.h
@@ -20,6 +20,9 @@ namespace ntimpl {
 class Storage;
 class Value;
 
+/*
+ * C++ wrapper class around NT_String.
+ */
 class StringValue : private NT_String {
   friend class Value;
  public:
@@ -27,8 +30,14 @@ class StringValue : private NT_String {
   ~StringValue() { NT_DisposeString(this); }
 
   operator llvm::StringRef() const { return llvm::StringRef(str, len); }
+
+  StringValue(const StringValue&) = delete;
+  StringValue& operator=(const StringValue&) = delete;
 };
 
+/*
+ * C++ wrapper class around NT_Value.
+ */
 class Value : private NT_Value {
   friend class Storage;
  public: