diff --git a/Readme.markdown b/Readme.markdown
index 62d2cf6..3a9e96b 100644
--- a/Readme.markdown
+++ b/Readme.markdown
@@ -49,6 +49,8 @@ alphanumerically and value from later files take precedence
   - `haddock` -- boolean flag on whether to build haddocks. Default is false.
   - `tests` -- boolean flag on whether to run tests when building
     package. Default is false.
+  - `jailbreak` -- boolean flag on whether to jailbreak packages. If true cabal
+    won't check dependencies' versions. Default is true.
 
 For example:
 
@@ -106,6 +108,9 @@ dummy dependency `testu01`. This allows to provide dependencies.
   splitmix = ... (prev.callPackage ./pkgs/haskell/splitmix.nix { testu01=null; });
 ```
 
+Field `jailbreak` could be specified for each package. It true nix package will
+be jailbroken (cabal won't check dependencies versions)
+
 * `patches` - contains patches that are applied to the nix files (will be modified in the future)
 
 Notes:
diff --git a/hackage.hs b/hackage.hs
index 8353366..3ed4bf6 100644
--- a/hackage.hs
+++ b/hackage.hs
@@ -93,13 +93,21 @@ data ConfigTests = ConfigTests
 
 type instance RuleResult ConfigTests = Bool
 
+-- | Key to obtain jailbreak
+data ConfigJailbreak = ConfigJailbreak
+  deriving stock    (Show, Eq, Generic)
+  deriving anyclass (Hashable, Binary, FromJSON, NFData)
+
+type instance RuleResult ConfigJailbreak = Bool
+
 
 data Config = Config
   { cfgRevision   :: !String -- ^ Hackage revision
   , cfgGhcVersion :: !String -- ^ GHC version to pass to cabal2nix
   , cfgProfile    :: !Bool   -- ^ Whether to build profiling
   , cfgHaddock    :: !Bool   -- ^ Whether to build haddocks
-  , cfgTests      :: !Bool
+  , cfgTests      :: !Bool   -- ^ Whether to enable tests
+  , cfgJailbreak  :: !Bool   -- ^ Whether to apply jailbreak to package
   }
   deriving stock    (Show, Eq, Generic)
   deriving anyclass (Hashable, Binary, NFData)
@@ -108,16 +116,18 @@ instance FromJSON Config where
   parseJSON = withObject "Config" $ \o -> do
     cfgRevision   <- o .: "revision"
     cfgGhcVersion <- o .: "ghc_version"
-    cfgProfile    <- o .:? "profile" .!= False
-    cfgHaddock    <- o .:? "haddock" .!= False
-    cfgTests      <- o .:? "tests"   .!= False
+    cfgProfile    <- o .:? "profile"   .!= False
+    cfgHaddock    <- o .:? "haddock"   .!= False
+    cfgTests      <- o .:? "tests"     .!= False
+    cfgJailbreak  <- o .:? "jailbreak" .!= True
     pure Config{..}
 
 
 -- | Information about package.
 data Package = Package
-  { packageSource :: Source   -- ^ Source location for package
-  , packageParams :: [String] -- ^ Code fragments to pass to package
+  { packageSource    :: Source   -- ^ Source location for package
+  , packageParams    :: [String] -- ^ Code fragments to pass to package
+  , packageJailbreak :: !Bool    -- ^ Whether to apply jailbreak to package
   }
   deriving stock    (Show, Eq, Generic)
   deriving anyclass (Hashable, Binary, NFData)
@@ -140,10 +150,11 @@ data Git = Git
 
 instance FromJSON Package where
   parseJSON v@String{}   = do src <- parseJSON v
-                              pure $ Package src []
+                              pure $ Package src [] True
   parseJSON v@(Object o) = do src   <- (SourceCabal <$> o .: "hackage") <|> parseJSON v
                               param <- o .:? "parameters" .!= []
-                              pure $ Package src param
+                              jail  <- o .:? "jailbreak"  .!= True
+                              pure $ Package src param jail
   parseJSON _ = fail "Cannot parse package"
 
 instance FromJSON Source where
@@ -193,11 +204,12 @@ main = do
       case nm `Map.lookup` repo_set of
         Just s  -> pure s
         Nothing -> error $ "No such repository: " ++ nm
-    get_revision <- addOracle $ \ConfigRevisionKey -> pure $ cfgRevision   config
-    get_ghcver   <- addOracle $ \ConfigGhcVersion  -> pure $ cfgGhcVersion config
-    get_profile  <- addOracle $ \ConfigProfile     -> pure $ cfgProfile    config
-    get_haddock  <- addOracle $ \ConfigHaddock     -> pure $ cfgHaddock    config
-    get_tests    <- addOracle $ \ConfigTests       -> pure $ cfgTests      config
+    get_revision  <- addOracle $ \ConfigRevisionKey -> pure $ cfgRevision   config
+    get_ghcver    <- addOracle $ \ConfigGhcVersion  -> pure $ cfgGhcVersion config
+    get_profile   <- addOracle $ \ConfigProfile     -> pure $ cfgProfile    config
+    get_haddock   <- addOracle $ \ConfigHaddock     -> pure $ cfgHaddock    config
+    get_tests     <- addOracle $ \ConfigTests       -> pure $ cfgTests      config
+    get_jailbreak <- addOracle $ \ConfigJailbreak   -> pure $ cfgJailbreak  config
     -- Phony targets
     phony "clean" $ do
       removeFilesAfter "nix/" ["pkgs/haskell/*.nix", "default.nix"]
@@ -257,16 +269,23 @@ main = do
       profile::String <- get_profile ConfigProfile <&> \case
         True  -> "lib.enableLibraryProfiling"
         False -> "lib.disableLibraryProfiling"
+      jailbreak::String <- get_jailbreak ConfigJailbreak <&> \case
+        True  -> "lib.doJailbreak"
+        False -> "lib.dontJailbreak"
       liftIO $ writeFile overlay $ unlines $ concat
         [ [ "pkgs: prev:"
           , "let"
           , "  lib = pkgs.haskell.lib;"
-          , [fmt|  adjust = drv: lib.doJailbreak ({profile} ({haddock} ({tests} drv)));|]
+          , [fmt|  adjust = drv: {jailbreak} ({profile} ({haddock} ({tests} drv)));|]
           , "in"
           , "{"
           ]
-        , [ [fmt|  {nm} = adjust (prev.callPackage ./{packageNixName nm} {{ {concat $ fmap (++";") param} }});|]
-          | (nm, Package{packageParams=param}) <- Map.toList pkgs_set
+        , [ [fmt|  {nm} = {fin};|]
+          | (nm, Package{packageParams=param,packageJailbreak=jail}) <- Map.toList pkgs_set
+          , let pkg,fin :: String
+                pkg = [fmt|adjust (prev.callPackage ./{packageNixName nm} {{ {concat $ fmap (++";") param} }})|]
+                fin | jail      = [fmt|lib.doJailbreak ({pkg})|]
+                    | otherwise = pkg
           ]
         , ["}"]
         ]