diff --git a/Data/StringMap.hs b/Data/StringMap.hs
--- a/Data/StringMap.hs
+++ b/Data/StringMap.hs
@@ -70,6 +70,7 @@
     , mapWithKey
     , mapM
     , mapWithKeyM
+    , mapMaybe
 
     -- * Folds
     , fold
diff --git a/Data/StringMap/Base.hs b/Data/StringMap/Base.hs
--- a/Data/StringMap/Base.hs
+++ b/Data/StringMap/Base.hs
@@ -91,6 +91,7 @@
         , mapWithKey
         , mapM
         , mapWithKeyM
+        , mapMaybe
 
         -- * Folds
         , fold
@@ -133,7 +134,7 @@
 import           Data.Binary
 import qualified Data.List      as L
 import qualified Data.Map       as M
-import           Data.Maybe
+import           Data.Maybe     hiding ( mapMaybe )
 
 import           Data.StringMap.Types
 import           Data.StringMap.StringSet
@@ -665,8 +666,23 @@
 map' f k (LsVal c  v)           = LsVal  c  (f (k []) v)
 map' f k (BrVal c  v n)         = BrVal  c  (f (k []) v)             (map' f k n)
 
--- ----------------------------------------
+-- | /O(n)/ Updates a value or deletes the element if the result of the updating function is 'Nothing'.
 
+mapMaybe                          :: (a -> Maybe b) -> StringMap a -> StringMap b
+mapMaybe                          = mapMaybe'
+
+{-# INLINE mapMaybe #-}
+
+mapMaybe'                       :: (a -> Maybe b) -> StringMap a -> StringMap b
+mapMaybe' f                     = upd . norm
+    where
+    upd'                        = mapMaybe' f
+    upd (Branch c' s' n')       = branch c' (upd' s') (upd' n')
+    upd Empty                   = empty
+    upd (Val v' t')             = maybe t (flip val t) $ f v'
+        where t = upd' t'
+    upd _                       = normError "update'"
+-- ----------------------------------------
 {- not yet used
 
 -- | Variant of map that works on normalized trees
diff --git a/Data/StringMap/Lazy.hs b/Data/StringMap/Lazy.hs
--- a/Data/StringMap/Lazy.hs
+++ b/Data/StringMap/Lazy.hs
@@ -89,6 +89,7 @@
     , mapWithKey
     , mapM
     , mapWithKeyM
+    , mapMaybe
 
     -- * Folds
     , fold
diff --git a/Data/StringMap/Strict.hs b/Data/StringMap/Strict.hs
--- a/Data/StringMap/Strict.hs
+++ b/Data/StringMap/Strict.hs
@@ -90,6 +90,7 @@
         , mapWithKey
         , mapM
         , mapWithKeyM
+        , mapMaybe
 
         -- * Folds
         , fold
diff --git a/data-stringmap.cabal b/data-stringmap.cabal
--- a/data-stringmap.cabal
+++ b/data-stringmap.cabal
@@ -1,9 +1,9 @@
 name:         data-stringmap
-version:      0.9
+version:      0.9.1
 license:      MIT
 license-file: LICENSE
-author:       Sebastian Philipp, Uwe Schmidt
-maintainer:   uwe@fh-wedel.de
+author:       Uwe Schmidt, Sebastian Philipp
+maintainer:   uwe@fh-wedel.de, sebastian@spawnhost.de
 bug-reports:  https://github.com/sebastian-philipp/StringMap/issues
 synopsis:     An efficient implementation of maps from strings to arbitrary values
 category:     Data Structures
diff --git a/tests/StringMapProperties.hs b/tests/StringMapProperties.hs
--- a/tests/StringMapProperties.hs
+++ b/tests/StringMapProperties.hs
@@ -50,6 +50,7 @@
        , testCase "differenceWithKey" test_differenceWithKey
        , testCase "map" test_map
        , testCase "mapWithKey" test_mapWithKey
+       , testCase "mapMaybe" test_mapMaybe
        -- , testCase "mapM" test_mapM
        -- , testCase "mapWithKeyM" test_mapWithKeyM
        , testCase "fold" test_fold
@@ -261,6 +262,13 @@
 test_mapWithKey :: Assertion
 test_mapWithKey =
     mapWithKey (mergeString "") (fromList [("a","A"), ("ab","B")]) @?= fromList [("ab", ":a|B"), ("a", ":a|A")]
+
+test_mapMaybe :: Assertion
+test_mapMaybe = do
+    mapMaybe (Just . (* 10)) (fromList [("a",_1), ("ab",2)]) @?= fromList [("a", 10), ("ab", 20)]
+    mapMaybe (f) (fromList [("a","A"), ("ab","B")]) @?= fromList [("a", 1::Int)]
+    where
+        f v = if v == "A" then Just 1 else Nothing
 
 test_mapM :: Assertion
 test_mapM = undefined