diff --git a/CM2005 Object Oriented Programming/Topic 5/5.1.9/Wallet.cpp b/CM2005 Object Oriented Programming/Topic 5/5.1.9/Wallet.cpp
index 48ebbd0..a2e2aef 100644
--- a/CM2005 Object Oriented Programming/Topic 5/5.1.9/Wallet.cpp	
+++ b/CM2005 Object Oriented Programming/Topic 5/5.1.9/Wallet.cpp	
@@ -60,7 +60,7 @@ bool Wallet::containsCurrency(std::string type, double amount)
 std::string Wallet::toString()
 {
   std::string s;
-  for(std::pair<std::string, double> pair : currencies)
+  for(std::pair<const std::string, double> pair : currencies)
   {
     std::string currency = pair.first;
     double amount = pair.second;
diff --git a/CM2005 Object Oriented Programming/Topic 5/5.1.9/a.exe b/CM2005 Object Oriented Programming/Topic 5/5.1.9/a.exe
index e7a47ed..28ef2fc 100644
Binary files a/CM2005 Object Oriented Programming/Topic 5/5.1.9/a.exe and b/CM2005 Object Oriented Programming/Topic 5/5.1.9/a.exe differ