diff --git a/misc/abacaba.lua b/misc/abacaba.lua
index b44743b..5887aa0 100644
--- a/misc/abacaba.lua
+++ b/misc/abacaba.lua
@@ -1,6 +1,6 @@
 if #arg < 1 then
-	print("iteration argument required")
-	return
+  print("iteration argument required")
+  return
 end
 
 alpha = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "q", "p", "q", "r", "s", "t", "u", "v", "x", "y", "z", }
@@ -8,7 +8,7 @@ prev_pttr = ""
 curr_pttr = ""
 iterations = arg[1] % #alpha
 for i = 1, iterations do
-	curr_pttr = prev_pttr .. alpha[i] .. prev_pttr
-	prev_pttr = curr_pttr
-	print(curr_pttr)
+  curr_pttr = prev_pttr .. alpha[i] .. prev_pttr
+  prev_pttr = curr_pttr
+  print(curr_pttr)
 end
diff --git a/misc/collatz.lua b/misc/collatz.lua
index 1f232c0..7028ec2 100644
--- a/misc/collatz.lua
+++ b/misc/collatz.lua
@@ -1,14 +1,14 @@
 function collatz(n)
-	io.write(n)
-	while n > 1 do
-		if (n % 2) == 0 then
-			n = n // 2
-		else
-			n = 3 * n + 1
-		end
-		io.write(' ' .. n)
-	end
-	io.write('\n')
+  io.write(n)
+  while n > 1 do
+    if (n % 2) == 0 then
+      n = n // 2
+    else
+      n = 3 * n + 1
+    end
+    io.write(' ' .. n)
+  end
+  io.write('\n')
 end
 
 assert(#arg ~= 0, 'expected initial number')
diff --git a/misc/luhn-lua/luhn.lua b/misc/luhn-lua/luhn.lua
index 416150e..c37490f 100644
--- a/misc/luhn-lua/luhn.lua
+++ b/misc/luhn-lua/luhn.lua
@@ -3,38 +3,38 @@ local luhn = {}
 
 -- main part of the algorithm, double each 2 digits, clamp them and return the sum.
 function luhn:_sum_digits(num)
-	assert(num >= 0, "number must be positive")
-	local sum = 0
-	local digits_n = 0
+  assert(num >= 0, "number must be positive")
+  local sum = 0
+  local digits_n = 0
 
-	repeat -- iterate over digits from right to left
-		local tmp = num % 10 -- get current unit
-		-- each 2 digits, double the current digit
-		if (digits_n % 2) == 0 then tmp = tmp * 2 end
-		if tmp > 9 then tmp = tmp - 9 end
+  repeat -- iterate over digits from right to left
+    local tmp = num % 10 -- get current unit
+    -- each 2 digits, double the current digit
+    if (digits_n % 2) == 0 then tmp = tmp * 2 end
+    if tmp > 9 then tmp = tmp - 9 end
 
-		digits_n = digits_n + 1
-		sum = sum + tmp
-		-- remove unit from number
-		num = math.floor(num / 10)
-	until num == 0
-	return sum
+    digits_n = digits_n + 1
+    sum = sum + tmp
+    -- remove unit from number
+    num = math.floor(num / 10)
+  until num == 0
+  return sum
 end
 
 -- returns the computed check digit
 function luhn:compute_check_digit(num)
-	return (self:_sum_digits(num) * 9) % 10
+  return (self:_sum_digits(num) * 9) % 10
 end
 
 -- returns true if its valid, false otherwise
 function luhn:validate_check_digit(num)
-	local check_digit = num % 10 -- get check digit
-	return self:compute_check_digit(math.floor(num / 10)) == check_digit
+  local check_digit = num % 10 -- get check digit
+  return self:compute_check_digit(math.floor(num / 10)) == check_digit
 end
 
 -- returns the original number with the check digit concatenated at the end
 function luhn:make_number(num)
-	return ((num * 10) + self:compute_check_digit(num))
+  return ((num * 10) + self:compute_check_digit(num))
 end
 
 return luhn
diff --git a/misc/luhn-lua/main.lua b/misc/luhn-lua/main.lua
index 4ec4c1f..d53d19e 100644
--- a/misc/luhn-lua/main.lua
+++ b/misc/luhn-lua/main.lua
@@ -2,12 +2,12 @@
 luhn = require "luhn"
 
 if #arg ~= 0 then
-	local a = tonumber(arg[1]) -- 7992739871
-	print("check digit: " .. luhn:compute_check_digit(a))
+  local a = tonumber(arg[1]) -- 7992739871
+  print("check digit: " .. luhn:compute_check_digit(a))
 end
 
 local function bool_str(bool)
-	return bool and "yes" or "no"
+  return bool and "yes" or "no"
 end
 
 print("49927398716: " .. bool_str(luhn:validate_check_digit(49927398716)))