diff --git a/src/main/java/command/ViewHistoryCommand.java b/src/main/java/command/ViewHistoryCommand.java
index 6fd558a38f..db72747b92 100644
--- a/src/main/java/command/ViewHistoryCommand.java
+++ b/src/main/java/command/ViewHistoryCommand.java
@@ -9,13 +9,19 @@ public ViewHistoryCommand(String[] commandParts) {
         super(false,commandParts);
     }
 
-    public String execute(TransactionManager manager) throws Exception{
+    public String execute(TransactionManager manager) throws Exception {
         //@@author Kishen271828
-        //String numTransactionsString = null;
         int numTransactions = 0;
         if (commandParts[1].startsWith("n/")) {
             String numTransactionsString = commandParts[1].substring(2);
-            numTransactions = Integer.parseInt(numTransactionsString);
+            try {
+                numTransactions = Integer.parseInt(numTransactionsString);
+                if (numTransactions <= 0) {
+                    throw new IllegalArgumentException("Sorry, please input a positive index.");
+                }
+            } catch (NumberFormatException e) {
+                throw new IncorrectCommandSyntaxException(commandParts[0]);
+            }
         } else if (commandParts[1].equals("all")) {
             numTransactions = manager.getTransactionListSize();
         } else {
diff --git a/src/main/java/financialtransactions/TransactionManager.java b/src/main/java/financialtransactions/TransactionManager.java
index 40a3d4fea1..b6ca9847b4 100644
--- a/src/main/java/financialtransactions/TransactionManager.java
+++ b/src/main/java/financialtransactions/TransactionManager.java
@@ -107,7 +107,7 @@ public Inflow editInflow(int index, Transaction<?> updatedTransaction) throws Ex
 
         inflows.editTransactionIndex(numOfInflows - index, (Inflow) updatedTransaction);
         inflows.sortTransactions();
-        return (Inflow) transactionEdited;
+        return transactionEdited;
     }
 
     public Outflow editOutflow(int index, Transaction<?> updatedTransaction) throws Exception {