diff --git a/controllers/accounts.go b/controllers/accounts.go
index cec4c5a..1ef451e 100644
--- a/controllers/accounts.go
+++ b/controllers/accounts.go
@@ -64,7 +64,7 @@ func unmarshalToAccount(r *http.Request, account *models.Account) error {
 	if err != nil {
 		return err
 	}
-	var validKey = regexp.MustCompile(`^[a-z_A-Z]+$`)
+	var validKey = regexp.MustCompile(`^[a-z_A-Z0-9]+$`)
 	for key := range account.Data {
 		if !validKey.MatchString(key) {
 			return fmt.Errorf("Invalid key in data json: %v", key)
diff --git a/controllers/transactions.go b/controllers/transactions.go
index 2d3fb5e..34e39ce 100644
--- a/controllers/transactions.go
+++ b/controllers/transactions.go
@@ -23,7 +23,7 @@ func unmarshalToTransaction(r *http.Request, txn *models.Transaction) error {
 	if err != nil {
 		return err
 	}
-	var validKey = regexp.MustCompile(`^[a-z_A-Z]+$`)
+	var validKey = regexp.MustCompile(`^[a-z_A-Z0-9]+$`)
 	for key := range txn.Data {
 		if !validKey.MatchString(key) {
 			return fmt.Errorf("Invalid key in data json: %v", key)