diff --git a/Test/Proctest.hs b/Test/Proctest.hs
--- a/Test/Proctest.hs
+++ b/Test/Proctest.hs
@@ -65,6 +65,8 @@
 
  -- * Running and stopping programs
 , run
+, RunException (..)
+, isRunning
 , terminateProcesses
 , closeHandles
 
@@ -116,13 +118,34 @@
 --
 -- Directly runs the process, does not use a shell.
 --
--- Sets the 'BufferMode to 'LineBuffering'.
+-- Sets the 'BufferMode to 'LineBuffering' if successful.
+--
+-- Throws 'CommandNotFound' if the command doesn't exist.
+-- Due to 'createProcess' not throwing an exception
+-- (<http://www.haskell.org/pipermail/haskell-cafe/2012-August/102824.html>),
+-- this is currently implemented by checking if the program
+-- returns early with error code 127.
 run :: FilePath -> [String] -> IO (Handle, Handle, Handle, ProcessHandle)
 run cmd args = do
-  r@(i, o, e, _) <- runInteractiveProcess cmd args Nothing Nothing
-  setBuffering LineBuffering [i, o, e]
-  return r
+  r@(i, o, e, p) <- runInteractiveProcess cmd args Nothing Nothing
+  getProcessExitCode p >>= \me -> case me of
+    -- TODO see if we can make runInteractiveProcess throw the exception instead
+    Just (ExitFailure 127) -> throwIO $ CommandNotFound cmd
+    _                      -> do
+      setBuffering LineBuffering [i, o, e]
+      return r
 
+-- | Exception to be thrown when a program could not be started.
+data RunException = CommandNotFound String
+                  | ExitedTooEarly String
+                    deriving (Show, Typeable)
+
+instance Exception RunException
+
+-- | Tells whether the given process is still running.
+isRunning :: ProcessHandle -> IO Bool
+isRunning p = do x <- getProcessExitCode p; return (x == Nothing)
+
 -- | Terminates all processes in the list.
 terminateProcesses :: [ProcessHandle] -> IO ()
 terminateProcesses = mapM_ terminateProcess
@@ -132,7 +155,7 @@
 closeHandles = mapM_ hClose
 
 
--- | A microsecnd timeout, or 'NoTimeout'.
+-- | A microsecond timeout, or 'NoTimeout'.
 data Timeout = NoTimeout | Micros Int
 
 -- | An error to be thrown if something is to be converted into timeout
@@ -141,7 +164,7 @@
 
 instance Exception InvalidTimeoutError
 
--- | Turns the given number of microsecnds into a 'Timeout'.
+-- | Turns the given number of microseconds into a 'Timeout'.
 --
 -- Throws an exception on 'Int' overflow.
 mkTimeoutUs :: Integer -> Timeout
@@ -173,7 +196,7 @@
 --
 -- Example: @(seconds 0.2)@ are roughly @Micros 200000@.
 seconds :: Float -> Timeout
-seconds s = mkTimeoutUs (round $ s * 10000000)
+seconds s = mkTimeoutUs (round $ s * 1000000)
 
 
 -- | Suspends execution for the given timeout; uses 'threadDelay' internally.
diff --git a/Test/Proctest/Assertions.hs b/Test/Proctest/Assertions.hs
new file mode 100644
--- /dev/null
+++ b/Test/Proctest/Assertions.hs
@@ -0,0 +1,42 @@
+{- | Helpers for asserting certain things for programs, using HUnit.
+
+All of the assertions in this module throw HUnit exceptions on failure
+using `assertFailure`.
+-}
+
+module Test.Proctest.Assertions (
+  -- * Starting programs
+    runAssert
+
+) where
+
+
+import Test.Proctest
+import Test.HUnit
+
+
+-- | Performs the monadic action on the contents of the `Just`, if any.
+onJust :: (Monad m) => (a -> m ()) -> Maybe a -> m ()
+onJust = maybe (return ())
+
+-- | Runs the given program with `run` and asserts that it is still running
+-- after the given timeout.
+--
+-- Don't choose the timeout too high as this function will block for it.
+--
+-- If the timeout is exceeded, a HUnit `assertFailure` exception is thrown,
+-- showing the command line to be invoked, the exit code, and the standard
+-- error output of the program.
+runAssert :: Timeout -> FilePath -> [String] -> IO (Handle, Handle, Handle, ProcessHandle)
+runAssert timeout cmd args = do
+  r@(_, _, hErr, p) <- run cmd args
+  sleep timeout
+  getProcessExitCode p >>= (onJust $ \ec -> do
+    -- The lazy IO here is OK, as we immediately show the String afterwards.
+    err <- hGetContents hErr
+    assertFailure $ "The program '" ++ program ++ "' after being started immediately "
+                    ++ "exited with exit code " ++ show ec ++ ".\n"
+                    ++ "--- stderr: ---\n" ++ err ++ "\n--- End of stderr ---")
+  return r
+  where
+    program = cmd ++ concatMap (" " ++) args
diff --git a/proctest.cabal b/proctest.cabal
--- a/proctest.cabal
+++ b/proctest.cabal
@@ -1,5 +1,5 @@
 name:          proctest
-version:       0.1.0.1
+version:       0.1.2.0
 license:       MIT
 license-file:  LICENSE
 author:        Niklas Hambüchen
@@ -29,12 +29,14 @@
 library
   default-language: Haskell2010
   exposed-modules:
-    Test.Proctest
+      Test.Proctest
+    , Test.Proctest.Assertions
   build-depends:
       base >= 4 && <= 5
     , process >= 1.1.0.1
     , bytestring
     , text
+    , HUnit
   ghc-options:
     -Wall
 
@@ -55,4 +57,3 @@
     , QuickCheck >= 2.4.2
   ghc-options:
     -threaded -fwarn-unused-imports
-