diff --git a/CHANGELOG.md b/CHANGELOG.md
index f1b661c97..9e0467777 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,8 +9,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Improved the error message of the currency code validation
+- Tightened the currency code validation by requiring uppercase letters
 - Renamed `Order` to `activities` in the `Account` database schema
 
+### Fixed
+
+- Improved the file selector of the activities import functionality to accept case-insensitive file extensions (`.CSV` and `.JSON`)
+
 ## 2.155.0 - 2025-04-23
 
 ### Added
diff --git a/apps/api/src/app/import/import.service.ts b/apps/api/src/app/import/import.service.ts
index babe7c3e3..b6fe0d949 100644
--- a/apps/api/src/app/import/import.service.ts
+++ b/apps/api/src/app/import/import.service.ts
@@ -167,9 +167,9 @@ export class ImportService {
 
       for (const account of accountsDto) {
         // Check if there is any existing account with the same ID
-        const accountWithSameId = existingAccounts.find(
-          (existingAccount) => existingAccount.id === account.id
-        );
+        const accountWithSameId = existingAccounts.find((existingAccount) => {
+          return existingAccount.id === account.id;
+        });
 
         // If there is no account or if the account belongs to a different user then create a new account
         if (!accountWithSameId || accountWithSameId.userId !== user.id) {
diff --git a/apps/api/src/validators/is-currency-code.ts b/apps/api/src/validators/is-currency-code.ts
index 34a82c481..d04da7808 100644
--- a/apps/api/src/validators/is-currency-code.ts
+++ b/apps/api/src/validators/is-currency-code.ts
@@ -25,19 +25,24 @@ export class IsExtendedCurrencyConstraint
   implements ValidatorConstraintInterface
 {
   public defaultMessage() {
-    return '$value must be a valid ISO4217 currency code';
+    return '$property must be a valid ISO4217 currency code';
   }
 
   public validate(currency: any) {
     // Return true if currency is a standard ISO 4217 code or a derived currency
     return (
-      isISO4217CurrencyCode(currency) ||
-      [
-        ...DERIVED_CURRENCIES.map((derivedCurrency) => {
-          return derivedCurrency.currency;
-        }),
-        'USX'
-      ].includes(currency)
+      this.isUpperCase(currency) &&
+      (isISO4217CurrencyCode(currency) ||
+        [
+          ...DERIVED_CURRENCIES.map((derivedCurrency) => {
+            return derivedCurrency.currency;
+          }),
+          'USX'
+        ].includes(currency))
     );
   }
+
+  private isUpperCase(aString: string) {
+    return aString === aString?.toUpperCase();
+  }
 }
diff --git a/apps/client/src/app/pages/portfolio/activities/import-activities-dialog/import-activities-dialog.component.ts b/apps/client/src/app/pages/portfolio/activities/import-activities-dialog/import-activities-dialog.component.ts
index 82e78a180..20f135801 100644
--- a/apps/client/src/app/pages/portfolio/activities/import-activities-dialog/import-activities-dialog.component.ts
+++ b/apps/client/src/app/pages/portfolio/activities/import-activities-dialog/import-activities-dialog.component.ts
@@ -247,9 +247,10 @@ export class ImportActivitiesDialog implements OnDestroy {
 
     reader.onload = async (readerEvent) => {
       const fileContent = readerEvent.target.result as string;
+      const fileExtension = file.name.split('.').pop()?.toLowerCase();
 
       try {
-        if (file.name.endsWith('.json')) {
+        if (fileExtension === 'json') {
           const content = JSON.parse(fileContent);
 
           this.accounts = content.accounts;
@@ -294,7 +295,7 @@ export class ImportActivitiesDialog implements OnDestroy {
           }
 
           return;
-        } else if (file.name.endsWith('.csv')) {
+        } else if (fileExtension === 'csv') {
           const content = fileContent.split('\n').slice(1);
 
           try {