diff --git a/Language/SystemVerilog/Parser/Preprocess.hs b/Language/SystemVerilog/Parser/Preprocess.hs
index f0fed29..29c1b5c 100644
--- a/Language/SystemVerilog/Parser/Preprocess.hs
+++ b/Language/SystemVerilog/Parser/Preprocess.hs
@@ -5,18 +5,18 @@ module Language.SystemVerilog.Parser.Preprocess
 
 -- | Remove comments from code.
 uncomment :: FilePath -> String -> String
-uncomment file a = uncomment a
+uncomment file str = uncomment' str
   where
-  uncomment a = case a of
+  uncomment' a = case a of
     ""               -> ""
     '/' : '/' : rest -> "  " ++ removeEOL rest
     '/' : '*' : rest -> "  " ++ remove rest
     '"'       : rest -> '"' : ignoreString rest
-    a         : rest -> a   : uncomment rest
+    ch        : rest -> ch  : uncomment' rest
 
   removeEOL a = case a of
     ""          -> ""
-    '\n' : rest -> '\n' : uncomment rest
+    '\n' : rest -> '\n' : uncomment' rest
     '\t' : rest -> '\t' : removeEOL rest
     _    : rest -> ' '  : removeEOL rest
 
@@ -25,7 +25,7 @@ uncomment file a = uncomment a
     '"' : rest       -> removeString rest
     '\n' : rest      -> '\n' : remove rest
     '\t' : rest      -> '\t' : remove rest
-    '*' : '/' : rest -> "  " ++ uncomment rest
+    '*' : '/' : rest -> "  " ++ uncomment' rest
     _ : rest         -> " "  ++ remove rest
 
   removeString a = case a of
@@ -38,17 +38,18 @@ uncomment file a = uncomment a
 
   ignoreString a = case a of
     ""                -> error $ "File ended without closing string: " ++ file
-    '"' : rest        -> '"' : uncomment rest
+    '"' : rest        -> '"' : uncomment' rest
     '\\' : '"' : rest -> "\\\"" ++ ignoreString rest
-    a : rest          -> a : ignoreString rest
+    ch : rest         -> ch : ignoreString rest
 
 -- | A simple `define preprocessor.
 preprocess :: [(String, String)] -> FilePath -> String -> String
-preprocess env file content = unlines $ pp True [] env $ lines $ uncomment file content
+preprocess _env file content = unlines $ pp True [] _env $ lines $ uncomment file content
   where
   pp :: Bool -> [Bool] -> [(String, String)] -> [String] -> [String]
   pp _ _ _ [] = []
   pp on stack env (a : rest) =
+    -- handle macros with escaped newlines
     if a /= "" && last a == '\\' && head a == '`'
     then "" : (pp on stack env $ ((init a) ++ " " ++ (head rest)) : (tail rest))
     else case words a of