diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,14 @@
 # Revision history for stopwatch
 
+## 0.1.0.1 -- 2016-05-03
+
+* Expand dependency version ranges for `transformers` and `clock`.
+
+* Loosen the test. Now it checks only lower bounds of the measured
+  delay, not upper bounds. This is because in some environments, it's
+  difficult to ensure the upper bounds.
+
+
 ## 0.1.0  -- 2015-09-13
 
 * First version. Released on an unsuspecting world.
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -8,6 +8,14 @@
 cabal configure --enable-tests && cabal build && cabal test
 ```
 
+## Important test flag
+
+- `test_delay_upper_bound`: Default: False. If True, the test checks
+  the return value of `stopWatch` with upper bounds. If False, it
+  doesn't check upper bounds. It checks lower bounds only.
+
+
+
 ## Author
 
 Toshio Ito <debug.ito@gmail.com>
diff --git a/stopwatch.cabal b/stopwatch.cabal
--- a/stopwatch.cabal
+++ b/stopwatch.cabal
@@ -1,5 +1,5 @@
 name:                   stopwatch
-version:                0.1.0
+version:                0.1.0.1
 author:                 Toshio Ito <debug.ito@gmail.com>
 maintainer:             Toshio Ito <debug.ito@gmail.com>
 license:                BSD3
@@ -16,12 +16,13 @@
 library
   default-language:     Haskell2010
   hs-source-dirs:       src
-  ghc-options:          -Wall
+  ghc-options:          -Wall -fno-warn-unused-imports
   exposed-modules:      Control.StopWatch
   -- other-modules:
   build-depends:        base >=2 && <6,
-                        transformers >=0.3.0 && <0.5,
-                        clock >=0.5 && <0.6
+                        transformers >=0.3.0 && <0.6,
+                        -- clock <0.5 is buggy!
+                        clock >=0.5 && <0.8
 
 -- executable stopwatch
 --   default-language:     Haskell2010
@@ -32,15 +33,28 @@
 --   -- other-extensions:    
 --   build-depends:        base >=4 && <5
 
+flag test_delay_upper_bound
+  description: Enable test of checking delay upper bound
+  default: False
+
+flag test_threaded
+  description: Enable -threaded option when building the test
+  default: False
+
 test-suite spec
   type:                 exitcode-stdio-1.0
   default-language:     Haskell2010
   hs-source-dirs:       test
-  ghc-options:          -Wall
+  if flag(test_threaded)
+    ghc-options:        -Wall -fno-warn-unused-imports "-with-rtsopts=-M512m" -threaded
+  else
+    ghc-options:        -Wall -fno-warn-unused-imports "-with-rtsopts=-M512m"
+  if flag(test_delay_upper_bound)
+    cpp-options:        -DTEST_DELAY_UPPER_BOUND
   main-is:              Spec.hs
   other-modules:        Control.StopWatchSpec
   build-depends:        base, stopwatch,
-                        hspec,
+                        hspec <2.3,
                         clock
 
 source-repository head
diff --git a/test/Control/StopWatchSpec.hs b/test/Control/StopWatchSpec.hs
--- a/test/Control/StopWatchSpec.hs
+++ b/test/Control/StopWatchSpec.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 module Control.StopWatchSpec (main, spec) where
 
 import Control.Concurrent (threadDelay)
@@ -5,21 +6,31 @@
 import Test.Hspec
 
 import Control.StopWatch (stopWatch)
-import System.Clock (sec, nsec)
+import System.Clock (TimeSpec(sec, nsec))
 
 main :: IO ()
 main = hspec spec
 
-testStopWatch :: Int -> Int -> Expectation
-testStopWatch threshold_range_msec target_msec = do
-  (_, difftime) <- stopWatch $ threadDelay (target_msec * 1000)
-  let got_diff_msec = fromIntegral $ (sec difftime) * 1000 + ((nsec difftime) `div` 1000000)
-  got_diff_msec `shouldSatisfy` (>= target_msec - threshold_range_msec)
-  got_diff_msec `shouldSatisfy` (<= target_msec + threshold_range_msec)
+checker :: Int -> Int -> (String, TimeSpec -> Bool)
+checker threshold_range_msec target_msec = (description, checker_func) where
+  ts2msec ts = fromIntegral $ (sec ts) * 1000 + ((nsec ts) `div` 1000000)
+#ifdef TEST_DELAY_UPPER_BOUND
+  description = "target " ++ (show target_msec) ++ "msec and range +- " ++ (show threshold_range_msec) ++ "msec"
+  checker_func got = (ts2msec got >= target_msec - threshold_range_msec)
+                     && (ts2msec got <= target_msec + threshold_range_msec)
+#else
+  description = "target " ++ (show target_msec) ++ "msec and lower bound -" ++ (show threshold_range_msec) ++ "msec"
+  checker_func got = (ts2msec got >= target_msec - threshold_range_msec)
+#endif
 
 specStopWatch :: Int -> Int -> Spec
-specStopWatch trange target = it ("should work for target " ++ (show target) ++ "msec and range " ++ (show trange) ++ "msec") $
-  testStopWatch trange target
+specStopWatch threshold_range_msec target_msec =
+  it ("should work for " ++ description) $ do
+    (_, difftime) <- stopWatch $ threadDelay (target_msec * 1000)
+    difftime `shouldSatisfy` checkerFunc
+  where
+    (description, checkerFunc) = checker threshold_range_msec target_msec
+    
 
 spec :: Spec
 spec = do