diff --git a/lib/iban-tools/iban.rb b/lib/iban-tools/iban.rb
index 4c44904..e1eeae9 100644
--- a/lib/iban-tools/iban.rb
+++ b/lib/iban-tools/iban.rb
@@ -52,18 +52,10 @@ def valid_check_digits?
     end
 
     def numerify
-      numerified = ""
-      (@code[4..-1] + @code[0..3]).each_byte do |byte|
-        numerified += case byte
-        # 0..9
-        when 48..57 then byte.chr
-        # 'A'..'Z'
-        when 65..90 then (byte - 55).to_s # 55 = 'A'.ord + 10
-        else
-          raise RuntimeError.new("Unexpected byte '#{byte}' in IBAN code '#{prettify}'")
-        end
+      if bad_match = @code.match(/[^A-Z0-9]/)
+        raise RuntimeError.new("Unexpected byte '#{bad_match[0].bytes.first}' in IBAN code '#{prettify}'")
       end
-      numerified
+      (@code[4..-1] + @code[0..3]).gsub(/[A-Z]/) { |let| (let.ord - 55).to_s }
     end
 
     def to_s
diff --git a/lib/iban-tools/rules.yml b/lib/iban-tools/rules.yml
index a41a4b2..3492d0c 100644
--- a/lib/iban-tools/rules.yml
+++ b/lib/iban-tools/rules.yml
@@ -20,6 +20,11 @@
   length: 20
   bban_pattern: '\d{16}'
 
+'AZ':
+  # Azerbaijan, Republic of
+  length: 28
+  bban_pattern: '\d[0-9]{2}[A-Z]{4}[A-Z0-9]{20}'
+
 'BA':
   # Bosnia
   length: 20
@@ -40,11 +45,21 @@
   length: 22
   bban_pattern: '[A-Z]{4}[A-Z0-9]{14}'
 
+'BR':
+  # Brazil
+  length: 29
+  bban_pattern: '\d[0-9]{2}[0-9]{8}[0-9]{5}[0-9]{10}[A-Z]{1}[A-Z0-9]{1}'
+
 'CH':
   # Switzerland
   length: 21
   bban_pattern: '\d{5}[A-Z0-9]{12}'
 
+'CR':
+  # Costa Rica
+  length: 21
+  bban_pattern: '\d[0-9]{2}[0-9]{3}[0-9]{14}'
+
 'CY':
   # Cyprus
   length: 28
@@ -120,6 +135,11 @@
   length: 27
   bban_pattern: '\d{7}[A-Z0-9]{16}'
 
+'GT':
+  # Guatemala
+  length: 28
+  bban_pattern: '\d[0-9]{2}[A-Z0-9]{4}[A-Z0-9]{20}'
+
 'HR':
   # Croatia
   length: 21
@@ -158,7 +178,7 @@
 'KZ':
   # Kazakhstan
   length: 20
-  bban_pattern: '\d{3}[A-Z]{3}\d{10}'
+  bban_pattern: '[0-9]{3}[A-Z0-9]{13}'
 
 'LB':
   # Lebanon
@@ -190,6 +210,11 @@
   length: 27
   bban_pattern: '\d{10}[A-Z0-9]{11}\d{2}'
 
+'MD':
+  # Moldova
+  length: 24
+  bban_pattern: '\d[0-9]{2}[A-Z0-9]{20}'
+
 'ME':
   # Montenegro
   length: 22
@@ -225,16 +250,31 @@
   length: 15
   bban_pattern: '\d{11}'
 
+'PK':
+  # Pakistan
+  length: 24
+  bban_pattern: '\d[0-9]{2}[A-Z]{4}[A-Z0-9]{16}'
+
 'PL':
   # Poland
   length: 28
   bban_pattern: '\d{8}[A-Z0-9]{16}'
 
+'PS':
+  # Palestinian Territory, Occupied
+  length: 29
+  bban_pattern: '\d[0-9]{2}[A-Z]{4}[A-Z0-9]{21}'
+
 'PT':
   # Portugal
   length: 25
   bban_pattern: '\d{21}'
 
+'QA':
+  # Qatar
+  length: 29
+  bban_pattern: '\d[0-9]{2}[A-Z]{4}[A-Z0-9]{21}'
+
 'RO':
   # Romania
   length: 24
@@ -270,6 +310,11 @@
   length: 27
   bban_pattern: '[A-Z]\d{10}[A-Z0-9]{12}'
 
+'TL':
+  # Timor-Leste
+  length: 23
+  bban_pattern: '\d[0-9]{2}[0-9]{3}[0-9]{14}[0-9]{2}'
+
 'TN':
   # Tunisia
   length: 24
@@ -280,3 +325,17 @@
   length: 26
   bban_pattern: '\d{5}[A-Z0-9]{17}'
 
+'UA':
+  # Ukraine
+  length: 29
+  bban_pattern: '\d{25}'
+
+'VG':
+  # Virgin Islands, British
+  length: 24
+  bban_pattern: '\d[0-9]{2}[A-Z]{4}[0-9]{16}'
+
+'XK':
+  # Kosovo, Republic of
+  length: 20
+  bban_pattern: '\d[0-9]{2}[0-9]{4}[A-Z0-9]{12}'
diff --git a/spec/iban-tools/iban_spec.rb b/spec/iban-tools/iban_spec.rb
index c796837..db5616d 100644
--- a/spec/iban-tools/iban_spec.rb
+++ b/spec/iban-tools/iban_spec.rb
@@ -89,11 +89,14 @@ module IBANTools
         "AE070331234567890123456",
         "AL47212110090000000235698741",
         "AT611904300234573201",
+        "AZ21NABZ00000000137010001944",
         "BA391290079401028494",
         "BE68539007547034",
         "BG80BNBG96611020345678",
         "BH67BMAG00001299123456",
+        "BR7724891749412660603618210F3",
         "CH9300762011623852957",
+        "CR0515202001026284066",
         "CY17002001280000001200527600",
         "CZ6508000000192000145399",
         "DE89370400440532013000",
@@ -109,6 +112,7 @@ module IBANTools
         "GI75NWBK000000007099453",
         "GL4330003330229543",
         "GR1601101250000000012300695",
+        "GT82TRAJ01020000001210029690",
         "HR1210010051863000160",
         "HU42117730161111101800000000",
         "IE29AIBK93115212345678",
@@ -123,6 +127,7 @@ module IBANTools
         "LU280019400644750000",
         "LV80BANK0000435195001",
         "MC1112739000700011111000h79",
+        "MD24AG000225100013104168",
         "ME25505000012345678951",
         "MK07300000000042425",
         "MR1300020001010000123456753",
@@ -130,8 +135,11 @@ module IBANTools
         "MU17BOMM0101101030300200000MUR",
         "NL91ABNA0417164300",
         "NO9386011117947",
+        "PK36SCBL0000001123456702",
         "PL27114020040000300201355387",
+        "PS92PALS000000000400123456702",
         "PT50000201231234567890154",
+        "QA58DOHB00001234567890ABCDEFG",
         "RO49AAAA1B31007593840000",
         "RS35260005601001611379",
         "SA0380000000608010167519",
@@ -139,8 +147,11 @@ module IBANTools
         "SI56191000000123438",
         "SK3112000000198742637541",
         "SM86U0322509800000000270100",
+        "TL380080012345678910157",
         "TN5914207207100707129648",
-        "TR330006100519786457841326"
+        "TR330006100519786457841326",
+        "VG96VPVG0000012345678901",
+        "XK051212012345678906"
       ].each do |iban_code| 
          describe iban_code do
            it "should be valid" do