diff --git a/src/compiler/GF/Compile/GetGrammar.hs b/src/compiler/GF/Compile/GetGrammar.hs
index c85f9588f..c7fea11b0 100644
--- a/src/compiler/GF/Compile/GetGrammar.hs
+++ b/src/compiler/GF/Compile/GetGrammar.hs
@@ -30,23 +30,71 @@ import Data.List (nub)
 import qualified Data.ByteString.Char8 as BS
 import Control.Monad (foldM)
 import System.Cmd (system)
+import System.Directory(removeFile)
 
 getSourceModule :: Options -> FilePath -> IOE SourceModule
 getSourceModule opts file0 = ioe $
-  catch (do file <- foldM runPreprocessor file0 (flag optPreprocessors opts)
-            content <- BS.readFile file
-            case runP pModDef content of
-              Left (Pn l c,msg) -> return (Bad (file++":"++show l++":"++show c++": "++msg))
-              Right mo          -> return (Ok (addOptionsToModule opts mo)))
-        (\e -> return (Bad (show e)))
+    do tmp <- foldM runPreprocessor (Source file0) (flag optPreprocessors opts)
+       content <- keepTemp tmp
+       case runP pModDef content of
+         Left (Pn l c,msg) -> do file <- writeTemp tmp
+                                 let location = file++":"++show l++":"++show c
+                                 return (Bad (location++": "++msg))
+         Right mo          -> do removeTemp tmp
+                                 return (Ok (addOptionsToModule opts mo))
+  `catch` (return . Bad . show)
 
 addOptionsToModule :: Options -> SourceModule -> SourceModule
 addOptionsToModule opts = mapSourceModule (\m -> m { flags = flags m `addOptions` opts })
 
--- FIXME: should use System.IO.openTempFile
-runPreprocessor :: FilePath -> String -> IO FilePath
-runPreprocessor file0 p = do
-  let tmp = "_gf_preproc.tmp"
-      cmd = p +++ file0 ++ ">" ++ tmp
-  system cmd
-  return tmp
+runPreprocessor :: Temporary -> String -> IO Temporary
+runPreprocessor tmp0 p =
+    maybe external internal (lookup p builtin_preprocessors)
+  where
+    internal preproc = (Internal . preproc) `fmap` readTemp tmp0
+    external =
+      do file0 <- writeTemp tmp0
+         -- FIXME: should use System.IO.openTempFile
+         let file1a = "_gf_preproc.tmp"
+             file1b = "_gf_preproc2.tmp"
+             -- file0 and file1 must be different
+             file1 = if file0==file1a then file1b else file1a
+             cmd = p +++ file0 ++ ">" ++ file1
+         system cmd
+         return (Temp file1)
+
+--------------------------------------------------------------------------------
+
+builtin_preprocessors = [("mkPresent",mkPresent),("mkMinimal",mkMinimal)]
+
+mkPresent = omit_lines "--# notpresent"   -- grep -v "\-\-\# notpresent"
+mkMinimal = omit_lines "--# notminimal"   -- grep -v "\-\-\# notminimal"
+
+omit_lines s = BS.unlines . filter (not . BS.isInfixOf bs) . BS.lines
+  where bs = BS.pack s
+
+--------------------------------------------------------------------------------
+
+data Temporary = Source FilePath | Temp FilePath | Internal BS.ByteString
+
+writeTemp tmp =
+    case tmp of
+      Source path  -> return path
+      Temp   path  -> return path
+      Internal str -> do -- FIXME: should use System.IO.openTempFile
+                         let tmp = "_gf_preproc.tmp"
+                         BS.writeFile tmp str
+                         return tmp
+
+readTemp tmp = do str <- keepTemp tmp
+                  removeTemp tmp
+                  return str
+
+keepTemp tmp =
+    case tmp of
+      Source path  -> BS.readFile path
+      Temp   path  -> BS.readFile path
+      Internal str -> return str
+
+removeTemp (Temp path) = removeFile path
+removeTemp _           = return ()
\ No newline at end of file