diff --git a/day4.cr b/day4.cr
index cdff746..b00a064 100644
--- a/day4.cr
+++ b/day4.cr
@@ -1,20 +1,6 @@
+require "./passports.cr"
 INPUT = File.read("day4.txt")
 
-def parse_passport(string)
-  new_hash = {} of String => String
-  string.split(" ").each do |field|
-    k,v = field.split(":")
-    new_hash[k] = v
-  end
-  new_hash
-end
-
-def parse_passports(lines)
-  lines.split(/\n\n/).map do |s|
-    parse_passport(s.chomp.gsub(/\n/, " "))
-  end
-end
-
 def part1
   input = INPUT.clone
   passports = parse_passports(input)
@@ -26,31 +12,11 @@ def part1
   puts total
 end
 
-def validate_range(range)
-  ->(s : String) { s.to_i32?.try { |i| range.includes? i } }
-end
-
-def validate_regex(regex)
-  ->(s : String) { s.matches?(regex) }
-end
-
 def part2
   input = INPUT.clone
   passports = parse_passports(input)
-  validators = {
-    "byr" => validate_range(1920..2002),
-    "iyr" => validate_range(2010..2020),
-    "eyr" => validate_range(2020..2030),
-    "hgt" => ->(s : String) {
-      return false unless s.match(/^(\d+)(cm|in)$/)
-      validate_range($~[2] == "cm" ? (150..193) : (59..76)).call($~[1])
-    },
-    "hcl" => validate_regex(/^#[0-9a-f]{6}$/),
-    "ecl" => ->(s : String) { "amb blu brn gry grn hzl oth".split(" ").includes? s },
-    "pid" => ->(s : String) { s =~ /^[0-9]{9}$/ },
-  }
   total = passports.count do |passport|
-    validators.all? do |k, v|
+    DEFAULT_VALIDATORS.all? do |k, v|
       passport[k]?.try { |s| v.call(s) }
     end
   end
diff --git a/passports.cr b/passports.cr
new file mode 100644
index 0000000..4ead063
--- /dev/null
+++ b/passports.cr
@@ -0,0 +1,39 @@
+def parse_passport(string)
+  new_hash = {} of String => String
+  string.split(" ").each do |field|
+    k,v = field.split(":")
+    new_hash[k] = v
+  end
+  new_hash
+end
+
+def parse_passports(lines)
+  lines.split(/\n\n/).map do |s|
+    parse_passport(s.chomp.gsub(/\n/, " "))
+  end
+end
+
+def validate_range(range)
+  ->(s : String) { s.to_i32?.try { |i| range.includes? i } }
+end
+
+def validate_regex(regex)
+  ->(s : String) { s.matches?(regex) }
+end
+
+def validate_unit_range(unit_ranges)
+  ->(s : String) {
+    return false unless s.match(/^(\d+)([a-zA-Z]+)$/)
+    unit_ranges[$~[2]]?.try { |rng| validate_range(rng).call($~[1]) }
+  }
+end
+
+DEFAULT_VALIDATORS = {
+  "byr" => validate_range(1920..2002),
+  "iyr" => validate_range(2010..2020),
+  "eyr" => validate_range(2020..2030),
+  "hgt" => validate_unit_range({"cm" => (150..193), "in" => (59..76)}),
+  "hcl" => validate_regex(/^#[0-9a-f]{6}$/),
+  "ecl" => ->(s : String) { "amb blu brn gry grn hzl oth".split(" ").includes? s },
+  "pid" => ->(s : String) { s =~ /^[0-9]{9}$/ },
+}