diff --git a/netpbm.cabal b/netpbm.cabal
--- a/netpbm.cabal
+++ b/netpbm.cabal
@@ -1,5 +1,5 @@
 name:          netpbm
-version:       0.2.0
+version:       0.2.1
 license:       MIT
 copyright:     2013 Niklas Hambüchen <mail@nh2.me>
 author:        Niklas Hambüchen <mail@nh2.me>
diff --git a/src/Graphics/Netpbm.hs b/src/Graphics/Netpbm.hs
--- a/src/Graphics/Netpbm.hs
+++ b/src/Graphics/Netpbm.hs
@@ -13,6 +13,7 @@
 , PPM (..)
 , PpmPixelRGB8
 , PpmPixelRGB16
+, PPMHeader (..)
 , PpmPixelData (..)
 , parsePPM
 , PpmParseResult
@@ -50,15 +51,18 @@
 
 -- | A PPM file with type, dimensions, and image data.
 data PPM = PPM {
-  ppmType :: PPMType
-, ppmWidth  :: {-# UNPACK #-} !Int
-, ppmHeight :: {-# UNPACK #-} !Int
+  ppmHeader :: PPMHeader
 , ppmData   :: PpmPixelData
 }
 
+data PPMHeader = PPMHeader {
+  ppmType   :: PPMType
+, ppmWidth  :: Int
+, ppmHeight :: Int
+} deriving (Eq, Show)
 
 instance Show PPM where
-  show PPM { ppmType, ppmWidth, ppmHeight } = "PPM " ++ show ppmType ++ " image " ++ dim
+  show PPM { ppmHeader = PPMHeader { ppmType, ppmWidth, ppmHeight } } = "PPM " ++ show ppmType ++ " image " ++ dim
     where
       dim = show (ppmWidth, ppmHeight)
 
@@ -162,9 +166,11 @@
   skipSpace
   comments
   width <- decimalC
+  comments
   skipSpace
   comments
   height <- decimalC
+  comments
   skipSpace
   comments
   maxColorVal <- decimalC
@@ -174,12 +180,13 @@
   _ <- A8.satisfy isSpace -- obligatory SINGLE whitespace
   -- Starting from here, comments are not allowed any more
   raster <- if maxColorVal < 256 -- 1 or 2 bytes per pixel
+      -- TODO check if values are smaller than maxColorVal
       then PpmPixelDataRGB8 <$> (U.replicateM (height * width) $
              PpmPixelRGB8 <$> anyWord8 <*> anyWord8 <*> anyWord8)
       else PpmPixelDataRGB16 <$> (U.replicateM (height * width) $
              PpmPixelRGB16 <$> anyWord16be <*> anyWord16be <*> anyWord16be)
 
-  return $ PPM ppmType width height raster
+  return $ PPM (PPMHeader ppmType width height) raster
 
   where
     isValidColorVal v = v > 0 && v < 65536
@@ -187,10 +194,10 @@
     comment = "#" .*> A.takeWhile isNotNewline <* endOfLine
     isNotNewline w = w /= 10 && w /= 13
     -- Decimal, possibly with comments interleaved,
-    -- but starting with a digit.
+    -- but starting and ending with a digit.
     -- See the notes about comments above.
     decimalC :: Parser Int
-    decimalC = foldl' shiftDecimalChar 0 <$> many1' (digit <* comments)
+    decimalC = foldl' shiftDecimalChar 0 <$> ((:) <$> digit <*> many (comments *> digit))
     shiftDecimalChar a d = a * 10 + ord d - (48 :: Int)
 
 
@@ -219,14 +226,15 @@
 -- and potentially an unparsable rest input.
 parsePPM :: ByteString -> PpmParseResult
 parsePPM bs = case parse imagesParser bs of
-  Done ""   images -> Right (images, Nothing)
-  Done rest images -> Right (images, Just rest)
-  Fail _ _ e       -> Left e
   -- The image file ByteStrings are not terminated by '\0',
   -- so Attoparsec will issue a Partial result when it
   -- parses to EOF. Passing in "" signalizes EOF.
-  Partial cont -> case cont "" of
-    Done ""   images -> Right (images, Nothing)
-    Done rest images -> Right (images, Just rest)
-    Partial _        -> error "parsePPM bug: Got a partial result after end of input"
-    Fail _ _ e       -> Left e
+  Partial cont -> resultToEither (cont "")
+  r            -> resultToEither r
+  where
+    -- Assumes a Partial result has already been fed with "" (another Partial cannot happen)
+    resultToEither r = case r of
+      Done ""   images -> Right (images, Nothing)
+      Done rest images -> Right (images, Just rest)
+      Partial _        -> error "parsePPM bug: Got a partial result after end of input"
+      Fail _ cs e      -> Left $ e ++ "; contexts: " ++ show cs
diff --git a/test/Main.hs b/test/Main.hs
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE NamedFieldPuns, OverloadedStrings #-}
 
 import qualified Data.ByteString as BS
 import           Control.Applicative
@@ -11,17 +11,23 @@
 
 checkSinglePPM :: PPMType -> (Int, Int) -> PpmParseResult -> Assertion
 checkSinglePPM typ size parseResult = case parseResult of
-  Right ([PPM { ppmType, ppmWidth, ppmHeight }], rest) -> (ppmType, (ppmWidth, ppmHeight), rest) `shouldBe` (typ, size, Nothing)
+  Right ([PPM { ppmHeader = PPMHeader { ppmType, ppmWidth, ppmHeight } }], rest) -> (ppmType, (ppmWidth, ppmHeight), rest) `shouldBe` (typ, size, Nothing)
   Right (ppms, _)                                      -> assertFailure $ "expected only one image, but got " ++ show (length ppms)
-  _                                                    -> assertFailure "image parse failed"
+  Left e                                               -> assertFailure $ "image parse failed: " ++ e
 
 
+shouldNotParse :: PpmParseResult -> Assertion
+shouldNotParse res = case res of
+  Left _ -> return ()
+  Right r -> assertFailure $ "should not parse, but parses as: " ++ show r
+
+
 parse :: FilePath -> IO PpmParseResult
 parse f = parsePPM <$> BS.readFile f
 
 
 parseTestFile :: String -> String -> (PpmParseResult -> Assertion) -> Spec
-parseTestFile name desc check = it ("parses " ++ desc ++ " (" ++ name ++ ")") $
+parseTestFile name desc check = it (desc ++ " (" ++ name ++ ")") $
   parse ("test/ppms/" ++ name) >>= check
 
 
@@ -41,8 +47,103 @@
     parseTestFile "testimg.ppm" "the color file from the netpbm test suite" $
       checkSinglePPM P6 (227,149)
 
-    parseTestFile "face.ppm" "a PPM with a trailing newline" $
-      checkSinglePPM P6 (512,512)
+    describe "more test files from the internet" $ do
+      forM_
+        [ ("boxes_1.ppm", (63,63))
+        , ("boxes_2.ppm", (63,63))
+        , ("house_1.ppm", (111,132))
+        , ("house_2.ppm", (111,132))
+        , ("moreboxes_1.ppm", (63,63))
+        , ("moreboxes_2.ppm", (63,63))
+        , ("sign_1.ppm", (99,99))
+        , ("sign_2.ppm", (99,99))
+        , ("stop_1.ppm", (99,99))
+        , ("stop_2.ppm", (99,99))
+        , ("synth_1.ppm", (100,100))
+        , ("synth_2.ppm", (100,100))
+        , ("tree_1.ppm", (133,133))
+        , ("tree_2.ppm", (133,133))
+        , ("west_1.ppm", (366,216))
+        , ("west_2.ppm", (366,216))
+        ] $ \(f, size) ->
+          parseTestFile ("internet/set1/" ++ f) "from the internet" $
+            checkSinglePPM P6 size
 
-    -- parseTestFile "gitlogo-double.ppm" "a multi-image file" $ do
-    --   checkSinglePPM P6 (220,92)
+
+    parseTestFile "gitlogo-double.ppm" "a multi-image file" $ do
+      \res -> case res of
+        Right ([ PPM { ppmHeader = h1 }
+               , PPM { ppmHeader = h2 }], rest) -> do h1 `shouldBe` PPMHeader P6 220 92
+                                                      h2 `shouldBe` PPMHeader P6 220 92
+                                                      rest `shouldBe` Nothing
+        Right r                                    -> assertFailure $ "parsed unexpected: " ++ show r
+        Left e                                     -> assertFailure $ "did not parse: " ++ e
+
+
+    describe "comments" $ do
+
+      parseTestFile "gitlogo-comments.ppm" "comments as a sane user would write them" $
+        checkSinglePPM P6 (220,92)
+
+      parseTestFile "gitlogo-comment-after-magic-number.ppm" "a comment directly after the P6" $
+        checkSinglePPM P6 (220,92)
+
+      parseTestFile "gitlogo-only-spaces-in-header.ppm" "only spaces as header separators" $
+        checkSinglePPM P6 (220,92)
+
+      parseTestFile "gitlogo-comment-is-data.ppm" "the user thinks they wrote a comment, but it's actually parsed as data" $
+        \res -> case res of
+          Right ([PPM { ppmHeader }], Just rest) -> do ppmHeader `shouldBe` PPMHeader P6 220 92
+                                                       rest `shouldBe` "\NUL\NUL\NUL\NUL\NUL\NUL\NUL\NUL\NUL\NUL\NUL\NUL\n"
+          Right r                                -> assertFailure $ "parsed unexpected: " ++ show r
+          Left e                                 -> assertFailure $ "did not parse: " ++ e
+
+
+    describe "weird files that are still OK with the spec" $ do
+
+      parseTestFile "weird/gitlogo-width-0.ppm" "width '00' set in an image" $
+        \res -> case res of
+          Right ([PPM { ppmHeader }], Just rest) -> do ppmHeader `shouldBe` PPMHeader P6 220 0
+                                                       assertBool "missing rest" (BS.length rest > 200)
+          Right r                                -> assertFailure $ "parsed unexpected: " ++ show r
+          Left e                                 -> assertFailure $ "did not parse: " ++ e
+
+      parseTestFile "weird/gitlogo-comments-everywhere.ppm" "comments inside numbers" $
+        checkSinglePPM P6 (220,92)
+
+
+    describe "partially valid files of which we parse as much as we can" $ do
+
+      parseTestFile "graceful/face.ppm" "a PPM with a trailing newline" $
+        checkSinglePPM P6 (512,512)
+
+      parseTestFile "graceful/gitlogo-one-and-a-half.ppm" "a multi-image file where the second image is chopped off" $
+        \res -> case res of
+          Right ([PPM { ppmHeader }], Just rest) -> do ppmHeader `shouldBe` PPMHeader P6 220 92
+                                                       assertBool "missing rest" (BS.length rest > 200)
+          Right r                                -> assertFailure $ "parsed unexpected: " ++ show r
+          Left e                                 -> assertFailure $ "did not parse: " ++ e
+
+      parseTestFile "graceful/gitlogo-double-with-whitespace-in-between.ppm" "a multi-image file with whitespace between the images" $
+        \res -> case res of
+          Right ([ PPM { ppmHeader = h1 }
+                 , PPM { ppmHeader = h2 }], rest) -> do h1 `shouldBe` PPMHeader P6 220 92
+                                                        h2 `shouldBe` PPMHeader P6 220 92
+                                                        rest `shouldBe` Nothing
+          Right r                                 -> assertFailure $ "parsed unexpected: " ++ show r
+          Left e                                  -> assertFailure $ "did not parse: " ++ e
+
+
+    describe "negative examples" $ do
+
+      parseTestFile "bad/gitlogo-garbage-in-numbers.ppm" "ascii characters in a number" shouldNotParse
+
+      parseTestFile "bad/gitlogo-width--1.ppm" "width '-1' set in an image" shouldNotParse
+
+      parseTestFile "bad/gitlogo-not-enough-data.ppm" "not containing (width * height) bytes" shouldNotParse
+
+      parseTestFile "bad/gitlogo-comment-in-magic-number.ppm" "comment inside magic number" shouldNotParse
+
+      parseTestFile "bad/gitlogo-comment-user-error.ppm" "a comment accidentally being put to close to a number, eating the following whitespace" $ shouldNotParse
+
+      parseTestFile "bad/gitlogo-comment-without-following-extra-newline-before-data-block.ppm" "no non-comment whitespace before data block" shouldNotParse