diff --git a/lib/Echidna/Campaign.hs b/lib/Echidna/Campaign.hs
index 3beedb00b..7e6e851ae 100644
--- a/lib/Echidna/Campaign.hs
+++ b/lib/Echidna/Campaign.hs
@@ -85,7 +85,7 @@ runWorker
   -> GenDict -- ^ Generation dictionary
   -> Int     -- ^ Worker id starting from 0
   -> [[Tx]]  -- ^ Initial corpus of transactions
-  -> Int     -- ^ Test limit for this worker
+  -> Maybe Int -- ^ Test limit for this worker
   -> m (WorkerStopReason, WorkerState)
 runWorker callback vm world dict workerId initialCorpus testLimit = do
   metaCacheRef <- asks (.metadataCache)
@@ -135,10 +135,10 @@ runWorker callback vm world dict workerId initialCorpus testLimit = do
     if | stopOnFail && any final tests ->
          lift callback >> pure FastFailed
 
-       | (null tests || any isOpen tests) && ncalls < testLimit ->
+       | (null tests || any isOpen tests) && maybe True (ncalls <) testLimit ->
          fuzz >> continue
 
-       | ncalls >= testLimit && any (\t -> isOpen t && isOptimizationTest t) tests -> do
+       | maybe False (ncalls >=) testLimit && any (\t -> isOpen t && isOptimizationTest t) tests -> do
          liftIO $ atomicModifyIORef' testsRef $ \sharedTests ->
             (closeOptimizationTest <$> sharedTests, ())
          continue
diff --git a/lib/Echidna/Config.hs b/lib/Echidna/Config.hs
index 05012ea27..f1fc80651 100644
--- a/lib/Echidna/Config.hs
+++ b/lib/Echidna/Config.hs
@@ -85,7 +85,7 @@ instance FromJSON EConfigWithUsage where
         pure $ TestConf classify (const psender)
 
       campaignConfParser = CampaignConf
-        <$> v ..:? "testLimit" ..!= defaultTestLimit
+        <$> v ..:? "testLimit"
         <*> v ..:? "stopOnFail" ..!= False
         <*> v ..:? "estimateGas" ..!= False
         <*> v ..:? "seqLen" ..!= defaultSequenceLength
diff --git a/lib/Echidna/Types/Campaign.hs b/lib/Echidna/Types/Campaign.hs
index 85f0ca478..72c802ff2 100644
--- a/lib/Echidna/Types/Campaign.hs
+++ b/lib/Echidna/Types/Campaign.hs
@@ -14,7 +14,7 @@ import Echidna.Types.Tx (Tx)
 
 -- | Configuration for running an Echidna 'Campaign'.
 data CampaignConf = CampaignConf
-  { testLimit       :: Int
+  { testLimit       :: Maybe Int
     -- ^ Maximum number of function calls to execute while fuzzing
   , stopOnFail      :: Bool
     -- ^ Whether to stop the campaign immediately if any property fails
@@ -116,9 +116,6 @@ initialWorkerState =
               , ncalls = 0
               }
 
-defaultTestLimit :: Int
-defaultTestLimit = 50000
-
 defaultSequenceLength :: Int
 defaultSequenceLength = 100
 
diff --git a/lib/Echidna/UI.hs b/lib/Echidna/UI.hs
index e8aadcc35..f10090f81 100644
--- a/lib/Echidna/UI.hs
+++ b/lib/Echidna/UI.hs
@@ -78,8 +78,10 @@ ui vm world dict initialCorpus = do
 
     -- Distribute over all workers, could be slightly bigger overall due to
     -- ceiling but this doesn't matter
-    perWorkerTestLimit = ceiling
-      (fromIntegral conf.campaignConf.testLimit / fromIntegral nworkers :: Double)
+    perWorkerTestLimit =
+      case conf.campaignConf.testLimit of
+        Nothing -> Nothing
+        Just t -> Just $ ceiling (fromIntegral t / fromIntegral nworkers :: Double)
 
     chunkSize = ceiling
       (fromIntegral (length initialCorpus) / fromIntegral nworkers :: Double)
diff --git a/lib/Echidna/UI/Widgets.hs b/lib/Echidna/UI/Widgets.hs
index 64f649515..46561ce43 100644
--- a/lib/Echidna/UI/Widgets.hs
+++ b/lib/Echidna/UI/Widgets.hs
@@ -159,8 +159,8 @@ summaryWidget env uiState =
       <=>
       perfWidget uiState
       <=>
-      str ("Total calls: " <> progress (sum $ (.ncalls) <$> uiState.campaigns)
-                                     env.cfg.campaignConf.testLimit)
+      str ("Total calls: " <> maybe (show totalCalls) (progress totalCalls) env.cfg.campaignConf.testLimit)
+  totalCalls = (sum $ (.ncalls) <$> uiState.campaigns)
   middle =
     padLeft (Pad 1) $
       str ("Unique instructions: " <> show uiState.coverage)
diff --git a/src/Main.hs b/src/Main.hs
index 5f4a50887..fcbc12d8a 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -275,7 +275,7 @@ options = Options
     <> help "Timeout given in seconds.")
   <*> optional (option auto $ long "test-limit"
     <> metavar "INTEGER"
-    <> help ("Number of sequences of transactions to generate during testing. Default is " ++ show defaultTestLimit))
+    <> help "Number of sequences of transactions to generate during testing. Default is unbounded.")
   <*> optional (option auto $ long "shrink-limit"
     <> metavar "INTEGER"
     <> help ("Number of tries to attempt to shrink a failing sequence of transactions. Default is " ++ show defaultShrinkLimit))
@@ -333,7 +333,7 @@ overrideConfig config Options{..} = do
 
     overrideCampaignConf campaignConf = campaignConf
       { corpusDir = cliCorpusDir <|> campaignConf.corpusDir
-      , testLimit = fromMaybe campaignConf.testLimit cliTestLimit
+      , testLimit = cliTestLimit <|> campaignConf.testLimit
       , shrinkLimit = fromMaybe campaignConf.shrinkLimit cliShrinkLimit
       , seqLen = fromMaybe campaignConf.seqLen cliSeqLen
       , seed = cliSeed <|> campaignConf.seed
diff --git a/src/test/Common.hs b/src/test/Common.hs
index b02e99045..2faf3a5cf 100644
--- a/src/test/Common.hs
+++ b/src/test/Common.hs
@@ -67,7 +67,7 @@ overrideQuiet conf =
 
 overrideLimits :: EConfig -> EConfig
 overrideLimits conf =
-  conf { campaignConf = conf.campaignConf { testLimit = 10000
+  conf { campaignConf = conf.campaignConf { testLimit = Just 10000
                                           , shrinkLimit = 4000 }}
 
 type SolcVersion = Version
diff --git a/src/test/Tests/Seed.hs b/src/test/Tests/Seed.hs
index 62ddddae2..b686977d0 100644
--- a/src/test/Tests/Seed.hs
+++ b/src/test/Tests/Seed.hs
@@ -21,7 +21,7 @@ seedTests =
     where
     cfg s = defaultConfig
       { campaignConf = CampaignConf
-        { testLimit = 600
+        { testLimit = Just 600
         , stopOnFail = False
         , estimateGas = False
         , seqLen = 20