diff --git a/src/GEval/BlackBoxDebugging.hs b/src/GEval/BlackBoxDebugging.hs
index 7102ca8..f03da5a 100644
--- a/src/GEval/BlackBoxDebugging.hs
+++ b/src/GEval/BlackBoxDebugging.hs
@@ -4,5 +4,6 @@ module GEval.BlackBoxDebugging
 
 data BlackBoxDebuggingOptions = BlackBoxDebuggingOptions {
   bbdoMinFrequency :: Integer,
-  bbdoWordShapes :: Bool
+  bbdoWordShapes :: Bool,
+  bbdoBigrams :: Bool
 }
diff --git a/src/GEval/FeatureExtractor.hs b/src/GEval/FeatureExtractor.hs
index 6e85476..4cbb645 100644
--- a/src/GEval/FeatureExtractor.hs
+++ b/src/GEval/FeatureExtractor.hs
@@ -2,8 +2,8 @@
 
 
 module GEval.FeatureExtractor
-  (extractUnigramFeatures,
-   extractUnigramFeaturesFromTabbed,
+  (extractFeatures,
+   extractFeaturesFromTabbed,
    Feature(..))
   where
 
@@ -13,10 +13,18 @@ import Data.Monoid ((<>))
 import Text.Tokenizer
 import Text.WordShape
 import GEval.BlackBoxDebugging
+import GEval.Common
 
-data Feature = SimpleFeature FeatureNamespace AtomicFeature
+data Feature = SimpleFeature FeatureNamespace SimpleFeature
                deriving (Eq, Ord)
 
+data SimpleFeature = SimpleAtomicFeature AtomicFeature | BigramFeature AtomicFeature AtomicFeature
+               deriving (Eq, Ord)
+
+instance Show SimpleFeature where
+  show (SimpleAtomicFeature feature) = show feature
+  show (BigramFeature featureA featureB) = (show featureA) ++ "++" ++ (show featureB)
+
 instance Show Feature where
   show (SimpleFeature namespace feature) = (show namespace) ++ ":" ++ (show feature)
 
@@ -46,15 +54,21 @@ extractAtomicFeatures mTokenizer bbdo t = [Data.List.map TextFeature tokens] ++
     else [])
   where tokens = nub $ (tokenizeForFeatures mTokenizer) t
 
+extractSimpleFeatures :: (Maybe Tokenizer) -> BlackBoxDebuggingOptions -> Text -> [SimpleFeature]
+extractSimpleFeatures mTokenizer bbdo t = Data.List.concat $ (Prelude.map (Prelude.map SimpleAtomicFeature) atomss) ++
+                                                             if bbdoBigrams bbdo
+                                                             then Prelude.map bigramFeatures atomss
+                                                             else []
+  where atomss = extractAtomicFeatures mTokenizer bbdo t
+        bigramFeatures atoms = Prelude.map (\(a, b) -> BigramFeature a b) $ bigrams atoms
 
-extractUnigramFeatures :: (Maybe Tokenizer) -> BlackBoxDebuggingOptions -> Text -> Text -> [Feature]
-extractUnigramFeatures mTokenizer bbdo namespace record =
+extractFeatures :: (Maybe Tokenizer) -> BlackBoxDebuggingOptions -> Text -> Text -> [Feature]
+extractFeatures mTokenizer bbdo namespace record =
   Prelude.map (\af -> SimpleFeature (FeatureNamespace namespace) af)
-  $ Data.List.concat
-  $ extractAtomicFeatures mTokenizer bbdo record
+  $ extractSimpleFeatures mTokenizer bbdo record
 
-extractUnigramFeaturesFromTabbed :: (Maybe Tokenizer) -> BlackBoxDebuggingOptions -> Text -> Text -> [Feature]
-extractUnigramFeaturesFromTabbed mTokenizer bbdo namespace record =
+extractFeaturesFromTabbed :: (Maybe Tokenizer) -> BlackBoxDebuggingOptions -> Text -> Text -> [Feature]
+extractFeaturesFromTabbed mTokenizer bbdo namespace record =
   Data.List.concat
-  $ Prelude.map (\(n, t) -> Prelude.map (\af -> SimpleFeature (FeatureTabbedNamespace namespace n) af) $ Data.List.concat $ extractAtomicFeatures mTokenizer bbdo t)
+  $ Prelude.map (\(n, t) -> Prelude.map (\af -> SimpleFeature (FeatureTabbedNamespace namespace n) af) $ extractSimpleFeatures mTokenizer bbdo t)
   $ Prelude.zip [1..] (splitOn "\t" record)
diff --git a/src/GEval/LineByLine.hs b/src/GEval/LineByLine.hs
index 00c2cba..0e26a3c 100644
--- a/src/GEval/LineByLine.hs
+++ b/src/GEval/LineByLine.hs
@@ -129,9 +129,9 @@ featureExtractor spec bbdo = CC.map extract .| CC.concat
   where extract (rank, LineRecord inLine expLine outLine _ score) =
           Prelude.map (\f -> RankedFeature f rank score)
           $ Data.List.concat [
-              extractUnigramFeatures mTokenizer bbdo "exp" expLine,
-              extractUnigramFeaturesFromTabbed mTokenizer bbdo "in" inLine,
-              extractUnigramFeatures mTokenizer bbdo "out" outLine]
+              extractFeatures mTokenizer bbdo "exp" expLine,
+              extractFeaturesFromTabbed mTokenizer bbdo "in" inLine,
+              extractFeatures mTokenizer bbdo "out" outLine]
         mTokenizer = gesTokenizer spec
 
 uScoresCounter :: Monad m => Integer -> ConduitT RankedFeature FeatureWithPValue (StateT Integer m) ()
diff --git a/src/GEval/OptionsParser.hs b/src/GEval/OptionsParser.hs
index cc2380d..91332ec 100644
--- a/src/GEval/OptionsParser.hs
+++ b/src/GEval/OptionsParser.hs
@@ -175,6 +175,9 @@ blackBoxDebuggingOptionsParser = BlackBoxDebuggingOptions
   <*> switch
     ( long "word-shapes"
       <> help "Consider word shapes")
+  <*> switch
+    ( long "bigrams"
+      <> help "Consider feature bigrams")
 
 singletonMaybe :: Maybe a -> Maybe [a]
 singletonMaybe (Just x) = Just [x]