diff --git a/README.md b/README.md
index e65730b..bfb0483 100644
--- a/README.md
+++ b/README.md
@@ -113,13 +113,13 @@ be wary of potential alignment issues.
 writes a series of 32-bit numbers until end-of-line.
 
 * `.align [n] [fill]`  
-aligns the next datum to a `n*2` boundary using `fill` for spacing.
-if `n` is not given, 2 is implied.
-if `fill` is not given, 0 is implied.
+aligns the next datum to a `2**n` boundary using `fill` for spacing.
+if `n` is omitted, 2 is implied.
+if `fill` is omitted, 0 is implied.
 
 * `.skip {n} [fill]`  
 skips the next `n` bytes using `fill` for spacing.
-if `fill` is not given, no bytes are overwritten,
+if `fill` is omitted, no bytes are overwritten,
 and only the position is changed.
 
 * `.org {address}`  
diff --git a/lips/Dumper.lua b/lips/Dumper.lua
index adb497c..ab86ac8 100644
--- a/lips/Dumper.lua
+++ b/lips/Dumper.lua
@@ -93,11 +93,13 @@ function Dumper:add_directive(line, name, a, b)
         self:advance(0)
     elseif name == 'ALIGN' then
         t.kind = 'ahead'
-        local align = a*2
-        if align == 0 then
+        local align
+        if a == 0 then
             align = 4
-        elseif align < 0 then
+        elseif a < 0 then
             self:error('negative alignment')
+        else
+            align = 2^a
         end
         local temp = self.pos + align - 1
         t.skip = temp - (temp % align) - self.pos