diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4ca8dfed..03e2e4ac 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Changed
+
+- Improved the error message of the currency code validation
+- Tightened the currency code validation by requiring uppercase letters
+
 ### Fixed
 
 - Improved the file selector of the activities import functionality to accept case-insensitive file extensions (`.CSV` and `.JSON`)
diff --git a/apps/api/src/validators/is-currency-code.ts b/apps/api/src/validators/is-currency-code.ts
index 34a82c48..d04da780 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();
+  }
 }