diff --git a/adventofcode.cabal b/adventofcode.cabal
index 8c583a3..ab4b735 100644
--- a/adventofcode.cabal
+++ b/adventofcode.cabal
@@ -28,15 +28,15 @@ library
   hs-source-dirs:
       src
   exposed-modules:
-      Day1
-      Day2
-      Day3
-      Day4
-      Day5
-      Day6
-      Day7
-      Day8
-      Day9
+      Day01
+      Day02
+      Day03
+      Day04
+      Day05
+      Day06
+      Day07
+      Day08
+      Day09
       Day10
   other-modules:
       Paths_adventofcode
diff --git a/app/Main.hs b/app/Main.hs
index 986b956..db88af5 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -8,13 +8,13 @@ import Text.PrettyPrint hiding ((<>))
 import System.Environment (getArgs)
 import qualified Data.Map as Map
 
-import qualified Day1
-import qualified Day2
-import qualified Day5
-import qualified Day6
-import qualified Day7
-import qualified Day8
-import qualified Day9
+import qualified Day01
+import qualified Day02
+import qualified Day05
+import qualified Day06
+import qualified Day07
+import qualified Day08
+import qualified Day09
 import qualified Day10
 
 showSol :: [Char] -> Doc -> IO ()
@@ -29,73 +29,73 @@ main = do
             (Map.lookup args solutions)
 
 solutions :: Map [[Char]] (IO ())
-solutions = Map.fromList [(["1"], day1)
-                         ,(["2"], day2)
-                         ,(["5"], day5)
-                         ,(["6"], day6)
-                         ,(["7"], day7)
-                         ,(["8"], day8)
-                         ,(["9"], day9)
+solutions = Map.fromList [(["01"], day01)
+                         ,(["02"], day02)
+                         ,(["05"], day05)
+                         ,(["06"], day06)
+                         ,(["07"], day07)
+                         ,(["08"], day08)
+                         ,(["09"], day09)
                          ,(["10"], day10)
                          ]
 
-day1 :: IO ()
-day1 = do
-  putText "Day 1:"
-  input1 <- Day1.ex1code
-  showSol "Solution 1" (int (Day1.solution1 input1))
-  showSol "Solution 2" (int (Day1.solution2 input1))
+day01 :: IO ()
+day01 = do
+  putText "Day 01:"
+  input1 <- Day01.ex1code
+  showSol "Solution 1" (int (Day01.solution1 input1))
+  showSol "Solution 2" (int (Day01.solution2 input1))
 
-day2 :: IO ()
-day2 = do
-  putText "Day 2:"
-  input <- Day2.parseInput
-  let sol1 = maybe 0 Day2.solution1 input
+day02 :: IO ()
+day02 = do
+  putText "Day 02:"
+  input <- Day02.parseInput
+  let sol1 = maybe 0 Day02.solution1 input
   showSol "Solution 1" (integer sol1)
-  let sol2 = maybe 0 Day2.solution2 input
+  let sol2 = maybe 0 Day02.solution2 input
   showSol "Solution 2" (integer sol2)
 
-day5 :: IO ()
-day5 = do
-  putText "Day 5:"
-  input5 <- Day5.parseInput
-  sol5 <- Day5.solution2 input5
+day05 :: IO ()
+day05 = do
+  putText "Day 05:"
+  input5 <- Day05.parseInput
+  sol5 <- Day05.solution2 input5
   showSol "Solution 2" (int sol5)
 
-day6 :: IO ()
-day6 = do
-  putText "Day 6:"
-  input6_1 <- Day6.parseInput
-  sol6_1 <- Day6.solution1 input6_1
+day06 :: IO ()
+day06 = do
+  putText "Day 06:"
+  input6_1 <- Day06.parseInput
+  sol6_1 <- Day06.solution1 input6_1
   showSol "Solution 1" (int sol6_1)
-  input6_2 <- Day6.parseInput
-  sol6_2 <- Day6.solution2 input6_2
+  input6_2 <- Day06.parseInput
+  sol6_2 <- Day06.solution2 input6_2
   showSol "Solution 2" (int sol6_2)
 
-day7 :: IO ()
-day7 = do
-  putText "Day 7:"
-  input <- Day7.parseInput
-  let sol_1 = Day7.rootOf input
-  showSol "Solution 1" (text (toS (maybe "" Day7.name sol_1)))
-  let sol_2 = Day7.solution2 input
+day07 :: IO ()
+day07 = do
+  putText "Day 07:"
+  input <- Day07.parseInput
+  let sol_1 = Day07.rootOf input
+  showSol "Solution 1" (text (toS (maybe "" Day07.name sol_1)))
+  let sol_2 = Day07.solution2 input
   showSol "Solution 2" (int (maybe 0 snd sol_2))
 
-day8 :: IO ()
-day8 = do
-  putText "Day 8:"
-  input <- Day8.parseInput
-  let sol1 = Day8.solution1 input
+day08 :: IO ()
+day08 = do
+  putText "Day 08:"
+  input <- Day08.parseInput
+  let sol1 = Day08.solution1 input
   showSol "Solution 1" (int sol1)
-  let sol2 = Day8.solution2 input
+  let sol2 = Day08.solution2 input
   showSol "Solution 2" (int sol2)
 
-day9 :: IO ()
-day9 = do
-  putText "Day 9:"
-  sol1 <- Day9.solution1
+day09 :: IO ()
+day09 = do
+  putText "Day 09:"
+  sol1 <- Day09.solution1
   showSol "Solution 1" (int sol1)
-  sol2 <- Day9.solution2
+  sol2 <- Day09.solution2
   showSol "Solution 2" (int sol2)
 
 day10 :: IO ()
diff --git a/package.yaml b/package.yaml
index cc1c044..19ac42a 100644
--- a/package.yaml
+++ b/package.yaml
@@ -13,15 +13,15 @@ extra-source-files:
 library:
   source-dirs: src
   exposed-modules:
-  - Day1
-  - Day2
-  - Day3
-  - Day4
-  - Day5
-  - Day6
-  - Day7
-  - Day8
-  - Day9
+  - Day01
+  - Day02
+  - Day03
+  - Day04
+  - Day05
+  - Day06
+  - Day07
+  - Day08
+  - Day09
   - Day10
   dependencies:
   - base >=4.7 && <5
diff --git a/src/Day1.hs b/src/Day01.hs
similarity index 97%
rename from src/Day1.hs
rename to src/Day01.hs
index d52e76d..74d3dec 100644
--- a/src/Day1.hs
+++ b/src/Day01.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE NoImplicitPrelude #-}
-module Day1 where
+module Day01 where
 
 import Protolude
 
diff --git a/src/Day2.hs b/src/Day02.hs
similarity index 99%
rename from src/Day2.hs
rename to src/Day02.hs
index 70a1412..9f025e7 100644
--- a/src/Day2.hs
+++ b/src/Day02.hs
@@ -45,7 +45,7 @@ In this example, the sum of the results would be 4 + 3 + 2 = 9.
 
 What is the sum of each row's result in your puzzle input?
 |-}
-module Day2 where
+module Day02 where
 
 import Protolude
 import qualified Control.Foldl as F
diff --git a/src/Day3.hs b/src/Day03.hs
similarity index 99%
rename from src/Day3.hs
rename to src/Day03.hs
index 20003c9..ac4ea3d 100644
--- a/src/Day3.hs
+++ b/src/Day03.hs
@@ -49,7 +49,7 @@ What is the first value written that is larger than your puzzle input?
 
 
 |-}
-module Day3 where
+module Day03 where
 
 import Protolude
 import qualified Control.Foldl as F
diff --git a/src/Day4.hs b/src/Day04.hs
similarity index 99%
rename from src/Day4.hs
rename to src/Day04.hs
index a65791d..2282279 100644
--- a/src/Day4.hs
+++ b/src/Day04.hs
@@ -34,7 +34,7 @@ oiii ioii iioi iiio is not valid - any of these words can be rearranged to form
 Under this new system policy, how many passphrases are valid?
 
 |-}
-module Day4 where
+module Day04 where
 
 import Protolude
 import qualified Data.Text as Text
diff --git a/src/Day5.hs b/src/Day05.hs
similarity index 99%
rename from src/Day5.hs
rename to src/Day05.hs
index 323cf6f..d7b9d7c 100644
--- a/src/Day5.hs
+++ b/src/Day05.hs
@@ -52,7 +52,7 @@ offset values after finding the exit are left as 2 3 2 3 -1.
 
 How many steps does it now take to reach the exit?
 |-}
-module Day5 where
+module Day05 where
 
 import           Protolude
 
diff --git a/src/Day6.hs b/src/Day06.hs
similarity index 99%
rename from src/Day6.hs
rename to src/Day06.hs
index 0447ca5..88066bd 100644
--- a/src/Day6.hs
+++ b/src/Day06.hs
@@ -59,7 +59,7 @@ How many cycles are in the infinite loop that arises from the configuration in
 your puzzle input?
 
 |-}
-module Day6 where
+module Day06 where
 
 import           Protolude
 
diff --git a/src/Day7.hs b/src/Day07.hs
similarity index 99%
rename from src/Day7.hs
rename to src/Day07.hs
index 809770f..2c23117 100644
--- a/src/Day7.hs
+++ b/src/Day07.hs
@@ -104,7 +104,7 @@ to be to balance the entire tower?
 
 
 |-}
-module Day7 where
+module Day07 where
 
 import           Protolude
 
diff --git a/src/Day8.hs b/src/Day08.hs
similarity index 99%
rename from src/Day8.hs
rename to src/Day08.hs
index 02cdc12..e4d19eb 100644
--- a/src/Day8.hs
+++ b/src/Day08.hs
@@ -35,7 +35,7 @@ What is the largest value in any register after completing the instructions in
 your puzzle input?
 
 |-}
-module Day8 where
+module Day08 where
 
 import           Protolude hiding ((<|>),many)
 
diff --git a/src/Day9.hs b/src/Day09.hs
similarity index 99%
rename from src/Day9.hs
rename to src/Day09.hs
index 03859b7..401ddf6 100644
--- a/src/Day9.hs
+++ b/src/Day09.hs
@@ -82,7 +82,7 @@ characters or the ! doing the canceling.
 How many non-canceled characters are within the garbage in your puzzle input?
 
 |-}
-module Day9 where
+module Day09 where
 
 import           Protolude hiding ((<|>),many)
 
diff --git a/test/Spec.hs b/test/Spec.hs
index 73ba997..235ac7d 100644
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -4,12 +4,12 @@ import Test.Tasty
 import Test.Tasty.HUnit
 import Control.Monad (when)
 
-import qualified Day1
-import qualified Day2
-import qualified Day5
-import qualified Day6
-import qualified Day7
-import qualified Day8
+import qualified Day01
+import qualified Day02
+import qualified Day05
+import qualified Day06
+import qualified Day07
+import qualified Day08
 import qualified Day10
 
 
@@ -19,67 +19,67 @@ main = defaultMain $
   [
   testGroup "Day 1"
   [ testGroup "solution 1"
-    [ testCase "1122 is 3" $ Day1.solution1 "1122" @?= 3
-    , testCase "1111 is 4" $ Day1.solution1 "1111" @?= 4
-    , testCase "1234 is 0" $ Day1.solution1 "1234" @?= 0
-    , testCase "91212129 is 9"  $ Day1.solution1 "91212129" @?= 9
+    [ testCase "1122 is 3" $ Day01.solution1 "1122" @?= 3
+    , testCase "1111 is 4" $ Day01.solution1 "1111" @?= 4
+    , testCase "1234 is 0" $ Day01.solution1 "1234" @?= 0
+    , testCase "91212129 is 9"  $ Day01.solution1 "91212129" @?= 9
     ]
   , testGroup "solution 2"
-    [ testCase "1212 is 6" $ Day1.solution2 "1212" @?= 6
-    , testCase "1221 is 0" $ Day1.solution2 "1221" @?= 0
-    , testCase "123425 is 0" $ Day1.solution2 "123425" @?= 4
-    , testCase "123123 is 12" $ Day1.solution2 "123123" @?= 12
-    , testCase "12131415 is 4" $ Day1.solution2 "12131415" @?= 4
+    [ testCase "1212 is 6" $ Day01.solution2 "1212" @?= 6
+    , testCase "1221 is 0" $ Day01.solution2 "1221" @?= 0
+    , testCase "123425 is 0" $ Day01.solution2 "123425" @?= 4
+    , testCase "123123 is 12" $ Day01.solution2 "123123" @?= 12
+    , testCase "12131415 is 4" $ Day01.solution2 "12131415" @?= 4
     ]
   ]
   , testGroup "Day 2"
     [ testCase "example problem 1" $
-      Day2.solution1 [[5,1,9,5],[7,5,3],[2,4,6,8]] @?= 18
+      Day02.solution1 [[5,1,9,5],[7,5,3],[2,4,6,8]] @?= 18
     ,  testCase "example problem 2" $
-      Day2.solution2 [[5,9,2,8],[9,4,7,3],[3,8,6,5]] @?= 9
+      Day02.solution2 [[5,9,2,8],[9,4,7,3],[3,8,6,5]] @?= 9
     ]
   , testGroup "Day 5"
     [ testCaseSteps "example problem 1" $ \step -> do
         step "Loading input"
-        input <- Day5.testArray
+        input <- Day05.testArray
         step "Running solution 1"
-        sol1 <- Day5.solution1 input
+        sol1 <- Day05.solution1 input
         when (sol1 /= 5) (assertFailure "Should be 5 steps")
     ,  testCaseSteps "example problem 2" $ \step -> do
         step "Loading input"
-        input <- Day5.testArray
+        input <- Day05.testArray
         step "Running solution 2"
-        sol2 <- Day5.solution2 input
+        sol2 <- Day05.solution2 input
         when (sol2 /= 10) (assertFailure "Day 6 solution 2 on the example should be 4")
     ]
   , testGroup "Day 6"
     [ testCaseSteps "example problem 1" $ \step -> do
         step "Loading input"
-        input <- Day6.testArray
+        input <- Day06.testArray
         step "Running solution 1"
-        sol1 <- Day6.solution1 input
+        sol1 <- Day06.solution1 input
         when (sol1 /= 5) (assertFailure "Should be 5 steps")
     ,  testCaseSteps "example problem 2" $ \step -> do
         step "Loading input"
-        input <- Day6.testArray
+        input <- Day06.testArray
         step "Running solution 2"
-        sol2 <- Day6.solution2 input
+        sol2 <- Day06.solution2 input
         when (sol2 /= 4) (assertFailure "Day 6 solution 2 on the example should be 4")
     ]
   , testGroup "Day 7"
     [ testCaseSteps "example problem 1" $ \step -> do
         step "Running solution 1"
-        let input = Day7.testNodes
-        let sol1 = maybe "" Day7.name (Day7.rootOf input)
+        let input = Day07.testNodes
+        let sol1 = maybe "" Day07.name (Day07.rootOf input)
         when (sol1 /= "tknk") (assertFailure "The root should be tknk")
     , testCase "example on solution 2" $
-       maybe 0 snd (Day7.solution2 Day7.testNodes) @?= 60
+       maybe 0 snd (Day07.solution2 Day07.testNodes) @?= 60
     ]
   , testGroup "Day 8"
     [ testCase "example problem 1" $
-        Day8.solution1 Day8.testInstructions @?= 1
+        Day08.solution1 Day08.testInstructions @?= 1
     , testCase "example problem 1" $
-        Day8.solution2 Day8.testInstructions @?= 10
+        Day08.solution2 Day08.testInstructions @?= 10
     ]
   , testGroup "Day 10"
     [ testCase "example 1" $