diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,13 @@
 Changes
 =======
 
+Version 0.10.1.1
+----------------
+
+* Prevent parsing non-positive number of threads via program options (#104)
+* Buffer output to avoid slowdowns when printing test results (#101)
+* Default to using the maximum number of available cores for test execution
+
 Version 0.10.1
 --------------
 
diff --git a/Test/Tasty/Ingredients/ConsoleReporter.hs b/Test/Tasty/Ingredients/ConsoleReporter.hs
--- a/Test/Tasty/Ingredients/ConsoleReporter.hs
+++ b/Test/Tasty/Ingredients/ConsoleReporter.hs
@@ -68,9 +68,10 @@
       level <- ask
 
       let
-        printTestName =
+        printTestName = do
           printf "%s%s: %s" (indent level) name
             (replicate (alignment - indentSize * level - length name) ' ')
+          hFlush stdout
 
         printTestResult result = do
           rDesc <- formatMessage $ resultDescription result
@@ -293,7 +294,7 @@
     then (do hideCursor; k) `finally` showCursor
     else k) $ do
 
-      hSetBuffering stdout NoBuffering
+      hSetBuffering stdout LineBuffering
 
       let
         whenColor = lookupOption opts
diff --git a/Test/Tasty/Options/Core.hs b/Test/Tasty/Options/Core.hs
--- a/Test/Tasty/Options/Core.hs
+++ b/Test/Tasty/Options/Core.hs
@@ -9,11 +9,13 @@
   )
   where
 
+import Control.Monad (mfilter)
 import Data.Typeable
 import Data.Proxy
 import Data.Tagged
 import Data.Fixed
 import Options.Applicative
+import GHC.Conc
 
 import Test.Tasty.Options
 import Test.Tasty.Patterns
@@ -28,8 +30,8 @@
 newtype NumThreads = NumThreads { getNumThreads :: Int }
   deriving (Eq, Ord, Num, Typeable)
 instance IsOption NumThreads where
-  defaultValue = 1
-  parseValue = fmap NumThreads . safeRead
+  defaultValue = NumThreads numCapabilities
+  parseValue = mfilter onlyPositive . fmap NumThreads . safeRead
   optionName = return "num-threads"
   optionHelp = return "Number of threads to use for tests execution"
   optionCLParser =
@@ -42,6 +44,10 @@
       name = untag (optionName :: Tagged NumThreads String)
       parse = str >>=
         maybe (readerError $ "Could not parse " ++ name) pure <$> parseValue
+
+-- | Filtering function to prevent non-positive number of threads
+onlyPositive :: NumThreads -> Bool
+onlyPositive (NumThreads x) = x > 0
 
 -- | Timeout to be applied to individual tests
 data Timeout
diff --git a/tasty.cabal b/tasty.cabal
--- a/tasty.cabal
+++ b/tasty.cabal
@@ -2,7 +2,7 @@
 --  see http://haskell.org/cabal/users-guide/
 
 name:                tasty
-version:             0.10.1
+version:             0.10.1.1
 synopsis:            Modern and extensible testing framework
 description:         Tasty is a modern testing framework for Haskell.
                      It lets you combine your unit tests, golden