diff --git a/types/iban/iban-tests.ts b/types/iban/iban-tests.ts
index ac79e97a99..574769c461 100644
--- a/types/iban/iban-tests.ts
+++ b/types/iban/iban-tests.ts
@@ -39,7 +39,7 @@ function testIsValidBBAN() {
  */
 function testPrintFormat() {
     var iban: string = 'BE68539007547034';
-    var separator: string[] = ['fr'];
+    var separator: string = ' ';
     var format: string = IBAN.printFormat(iban, separator);
 }
 
@@ -48,6 +48,6 @@ function testPrintFormat() {
  */
 function testToBBAN() {
     var iban: string = 'BE68539007547034';
-    var separator: string[] = ['-'];
+    var separator: string = '-';
     var bban: string = IBAN.toBBAN(iban, separator);
-}
\ No newline at end of file
+}
diff --git a/types/iban/index.d.ts b/types/iban/index.d.ts
index a47cfa618f..2b14d73954 100644
--- a/types/iban/index.d.ts
+++ b/types/iban/index.d.ts
@@ -42,17 +42,17 @@ interface IBANStatic {
     /** 
      * @summary Returns the IBAN in a print format.
      * @param {string} iban The IBAN to convert.
-     * @param {string} The IBAN in print format.
+     * @param {string} separator The separator to use between IBAN blocks, defaults to ' '.
      */
-    printFormat(iban: string, separator: string[]): string;
+    printFormat(iban: string, separator?: string): string;
 
     /**
      * @summary Convert the passed IBAN to a country-specific BBAN.
      * @param {string} iban The IBAN to convert.
-     * @param {string[]} Separator the separator to use between BBAN blocks.
+     * @param {string} separator The separator to use between BBAN blocks, defaults to ' '.
      * @returns {string} The BBAN
      */
-    toBBAN(iban: string, separator: string[]): string;
+    toBBAN(iban: string, separator?: string): string;
 }
 
 declare var IBAN: IBANStatic;