diff --git a/System/FilePath/Internal.hs b/System/FilePath/Internal.hs
index c3dcb863..bce55063 100644
--- a/System/FilePath/Internal.hs
+++ b/System/FilePath/Internal.hs
@@ -927,6 +927,10 @@ badElements =
 -- > Windows: isValid "\\\\\\foo" == False
 -- > Windows: isValid "\\\\?\\D:file" == False
 -- > Windows: isValid "foo\tbar" == False
+-- > Windows: isValid "foo." == False
+-- > Windows: isValid "foo " == False
+-- > Windows: isValid "foo.\\bar" == False
+-- > Windows: isValid "foo \\bar" == False
 -- > Windows: isValid "nul .txt" == False
 -- > Windows: isValid " nul.txt" == True
 isValid :: FilePath -> Bool
@@ -936,11 +940,15 @@ isValid _ | isPosix = True
 isValid path =
         not (any isBadCharacter x2) &&
         not (any f $ splitDirectories x2) &&
+        not (any g $ splitDirectories x2) &&
         not (isJust (readDriveShare x1) && all isPathSeparator x1) &&
         not (isJust (readDriveUNC x1) && not (hasTrailingPathSeparator x1))
     where
         (x1,x2) = splitDrive path
         f x = map toUpper (dropWhileEnd (== ' ') $ dropExtensions x) `elem` badElements
+        g "." = False
+        g ".." = False
+        g x = head (reverse $ '@' : x) `elem` ". "
 
 
 -- | Take a FilePath and make it valid; does not change already valid FilePaths.
@@ -952,6 +960,8 @@ isValid path =
 -- > Windows: makeValid "c:\\already\\/valid" == "c:\\already\\/valid"
 -- > Windows: makeValid "c:\\test:of_test" == "c:\\test_of_test"
 -- > Windows: makeValid "test*" == "test_"
+-- > Windows: makeValid "test." == "test._"
+-- > Windows: makeValid "test " == "test _"
 -- > Windows: makeValid "c:\\test\\nul" == "c:\\test\\nul_"
 -- > Windows: makeValid "c:\\test\\prn.txt" == "c:\\test\\prn_.txt"
 -- > Windows: makeValid "c:\\test/prn.txt" == "c:\\test/prn_.txt"
@@ -974,10 +984,13 @@ makeValid path
         f x = if isBadCharacter x then '_' else x
 
         validElements x = joinPath $ map g $ splitPath x
-        g x = h a ++ b
+        g x = i (h a) ++ b
             where (a,b) = break isPathSeparator x
         h x = if map toUpper (dropWhileEnd (== ' ') a) `elem` badElements then a ++ "_" <.> b else x
             where (a,b) = splitExtensions x
+        i "." = "."
+        i ".." = ".."
+        i x = if head (reverse $ '@' : x) `elem` ". " then x ++ "_" else x
 
 
 -- | Is a path relative, or is it fixed to the root?
diff --git a/System/FilePath/Posix.hs b/System/FilePath/Posix.hs
index 219f7d19..becb0d11 100644
--- a/System/FilePath/Posix.hs
+++ b/System/FilePath/Posix.hs
@@ -927,6 +927,10 @@ badElements =
 -- > Windows: isValid "\\\\\\foo" == False
 -- > Windows: isValid "\\\\?\\D:file" == False
 -- > Windows: isValid "foo\tbar" == False
+-- > Windows: isValid "foo." == False
+-- > Windows: isValid "foo " == False
+-- > Windows: isValid "foo.\\bar" == False
+-- > Windows: isValid "foo \\bar" == False
 -- > Windows: isValid "nul .txt" == False
 -- > Windows: isValid " nul.txt" == True
 isValid :: FilePath -> Bool
@@ -936,11 +940,15 @@ isValid _ | isPosix = True
 isValid path =
         not (any isBadCharacter x2) &&
         not (any f $ splitDirectories x2) &&
+        not (any g $ splitDirectories x2) &&
         not (isJust (readDriveShare x1) && all isPathSeparator x1) &&
         not (isJust (readDriveUNC x1) && not (hasTrailingPathSeparator x1))
     where
         (x1,x2) = splitDrive path
         f x = map toUpper (dropWhileEnd (== ' ') $ dropExtensions x) `elem` badElements
+        g "." = False
+        g ".." = False
+        g x = head (reverse $ '@' : x) `elem` ". "
 
 
 -- | Take a FilePath and make it valid; does not change already valid FilePaths.
@@ -952,6 +960,8 @@ isValid path =
 -- > Windows: makeValid "c:\\already\\/valid" == "c:\\already\\/valid"
 -- > Windows: makeValid "c:\\test:of_test" == "c:\\test_of_test"
 -- > Windows: makeValid "test*" == "test_"
+-- > Windows: makeValid "test." == "test._"
+-- > Windows: makeValid "test " == "test _"
 -- > Windows: makeValid "c:\\test\\nul" == "c:\\test\\nul_"
 -- > Windows: makeValid "c:\\test\\prn.txt" == "c:\\test\\prn_.txt"
 -- > Windows: makeValid "c:\\test/prn.txt" == "c:\\test/prn_.txt"
@@ -974,10 +984,13 @@ makeValid path
         f x = if isBadCharacter x then '_' else x
 
         validElements x = joinPath $ map g $ splitPath x
-        g x = h a ++ b
+        g x = i (h a) ++ b
             where (a,b) = break isPathSeparator x
         h x = if map toUpper (dropWhileEnd (== ' ') a) `elem` badElements then a ++ "_" <.> b else x
             where (a,b) = splitExtensions x
+        i "." = "."
+        i ".." = ".."
+        i x = if head (reverse $ '@' : x) `elem` ". " then x ++ "_" else x
 
 
 -- | Is a path relative, or is it fixed to the root?
diff --git a/System/FilePath/Windows.hs b/System/FilePath/Windows.hs
index 56aa7197..c085c8e5 100644
--- a/System/FilePath/Windows.hs
+++ b/System/FilePath/Windows.hs
@@ -927,6 +927,10 @@ badElements =
 -- > Windows: isValid "\\\\\\foo" == False
 -- > Windows: isValid "\\\\?\\D:file" == False
 -- > Windows: isValid "foo\tbar" == False
+-- > Windows: isValid "foo." == False
+-- > Windows: isValid "foo " == False
+-- > Windows: isValid "foo.\\bar" == False
+-- > Windows: isValid "foo \\bar" == False
 -- > Windows: isValid "nul .txt" == False
 -- > Windows: isValid " nul.txt" == True
 isValid :: FilePath -> Bool
@@ -936,11 +940,15 @@ isValid _ | isPosix = True
 isValid path =
         not (any isBadCharacter x2) &&
         not (any f $ splitDirectories x2) &&
+        not (any g $ splitDirectories x2) &&
         not (isJust (readDriveShare x1) && all isPathSeparator x1) &&
         not (isJust (readDriveUNC x1) && not (hasTrailingPathSeparator x1))
     where
         (x1,x2) = splitDrive path
         f x = map toUpper (dropWhileEnd (== ' ') $ dropExtensions x) `elem` badElements
+        g "." = False
+        g ".." = False
+        g x = head (reverse $ '@' : x) `elem` ". "
 
 
 -- | Take a FilePath and make it valid; does not change already valid FilePaths.
@@ -952,6 +960,8 @@ isValid path =
 -- > Windows: makeValid "c:\\already\\/valid" == "c:\\already\\/valid"
 -- > Windows: makeValid "c:\\test:of_test" == "c:\\test_of_test"
 -- > Windows: makeValid "test*" == "test_"
+-- > Windows: makeValid "test." == "test._"
+-- > Windows: makeValid "test " == "test _"
 -- > Windows: makeValid "c:\\test\\nul" == "c:\\test\\nul_"
 -- > Windows: makeValid "c:\\test\\prn.txt" == "c:\\test\\prn_.txt"
 -- > Windows: makeValid "c:\\test/prn.txt" == "c:\\test/prn_.txt"
@@ -974,10 +984,13 @@ makeValid path
         f x = if isBadCharacter x then '_' else x
 
         validElements x = joinPath $ map g $ splitPath x
-        g x = h a ++ b
+        g x = i (h a) ++ b
             where (a,b) = break isPathSeparator x
         h x = if map toUpper (dropWhileEnd (== ' ') a) `elem` badElements then a ++ "_" <.> b else x
             where (a,b) = splitExtensions x
+        i "." = "."
+        i ".." = ".."
+        i x = if head (reverse $ '@' : x) `elem` ". " then x ++ "_" else x
 
 
 -- | Is a path relative, or is it fixed to the root?
diff --git a/changelog.md b/changelog.md
index 6026f3b1..b89c59d6 100644
--- a/changelog.md
+++ b/changelog.md
@@ -2,6 +2,11 @@
 
 _Note: below all `FilePath` values are unquoted, so `\\` really means two backslashes._
 
+## 1.5.0.0 *WIP*
+
+* breaking changes:
+	- Make `Windows.isValid` reject paths ending in a dot or space wrt [#94](https://github.com/haskell/filepath/pull/94)
+
 ## 1.4.2.2 *WIP*
 
 * Document relation between `joinPath` and `(</>)` wrt [#82](https://github.com/haskell/filepath/issues/82), [#82](https://github.com/haskell/filepath/issues/86)
diff --git a/filepath.cabal b/filepath.cabal
index e75a4cf8..d4e574cf 100644
--- a/filepath.cabal
+++ b/filepath.cabal
@@ -1,6 +1,6 @@
 cabal-version:  1.18
 name:           filepath
-version:        1.4.2.2
+version:        1.5.0.0
 -- NOTE: Don't forget to update ./changelog.md
 license:        BSD3
 license-file:   LICENSE
diff --git a/tests/TestGen.hs b/tests/TestGen.hs
index 62eb18f4..e00dd71e 100755
--- a/tests/TestGen.hs
+++ b/tests/TestGen.hs
@@ -427,6 +427,10 @@ tests =
     ,("W.isValid \"\\\\\\\\\\\\foo\" == False", property $ W.isValid "\\\\\\foo" == False)
     ,("W.isValid \"\\\\\\\\?\\\\D:file\" == False", property $ W.isValid "\\\\?\\D:file" == False)
     ,("W.isValid \"foo\\tbar\" == False", property $ W.isValid "foo\tbar" == False)
+    ,("W.isValid \"foo.\" == False", property $ W.isValid "foo." == False)
+    ,("W.isValid \"foo \" == False", property $ W.isValid "foo " == False)
+    ,("W.isValid \"foo.\\\\bar\" == False", property $ W.isValid "foo.\\bar" == False)
+    ,("W.isValid \"foo \\\\bar\" == False", property $ W.isValid "foo \\bar" == False)
     ,("W.isValid \"nul .txt\" == False", property $ W.isValid "nul .txt" == False)
     ,("W.isValid \" nul.txt\" == True", property $ W.isValid " nul.txt" == True)
     ,("P.isValid (P.makeValid x)", property $ \(QFilePath x) -> P.isValid (P.makeValid x))
@@ -440,6 +444,8 @@ tests =
     ,("W.makeValid \"c:\\\\already\\\\/valid\" == \"c:\\\\already\\\\/valid\"", property $ W.makeValid "c:\\already\\/valid" == "c:\\already\\/valid")
     ,("W.makeValid \"c:\\\\test:of_test\" == \"c:\\\\test_of_test\"", property $ W.makeValid "c:\\test:of_test" == "c:\\test_of_test")
     ,("W.makeValid \"test*\" == \"test_\"", property $ W.makeValid "test*" == "test_")
+    ,("W.makeValid \"test.\" == \"test._\"", property $ W.makeValid "test." == "test._")
+    ,("W.makeValid \"test \" == \"test _\"", property $ W.makeValid "test " == "test _")
     ,("W.makeValid \"c:\\\\test\\\\nul\" == \"c:\\\\test\\\\nul_\"", property $ W.makeValid "c:\\test\\nul" == "c:\\test\\nul_")
     ,("W.makeValid \"c:\\\\test\\\\prn.txt\" == \"c:\\\\test\\\\prn_.txt\"", property $ W.makeValid "c:\\test\\prn.txt" == "c:\\test\\prn_.txt")
     ,("W.makeValid \"c:\\\\test/prn.txt\" == \"c:\\\\test/prn_.txt\"", property $ W.makeValid "c:\\test/prn.txt" == "c:\\test/prn_.txt")