diff --git a/ChangeLog.md b/ChangeLog.md
new file mode 100644
--- /dev/null
+++ b/ChangeLog.md
@@ -0,0 +1,8 @@
+# ChangeLog for crypton-x509-system
+
+## 1.6.8
+
+* Prefer OpenSSL env vars: SSL_CERT_FILE and SSL_CERT_DIR
+  [#26](https://github.com/kazu-yamamoto/crypton-certificate/pull/26)
+* Unix defaultSystemPaths: add new Fedora default cert filepath
+  [#19](https://github.com/kazu-yamamoto/crypton-certificate/pull/19)
diff --git a/Setup.hs b/Setup.hs
--- a/Setup.hs
+++ b/Setup.hs
@@ -1,2 +1,3 @@
 import Distribution.Simple
+
 main = defaultMain
diff --git a/System/X509.hs b/System/X509.hs
--- a/System/X509.hs
+++ b/System/X509.hs
@@ -1,14 +1,14 @@
 {-# LANGUAGE CPP #-}
+
 -- |
 -- Module      : System.X509
 -- License     : BSD-style
 -- Maintainer  : Vincent Hanquez <vincent@snarc.org>
 -- Stability   : experimental
 -- Portability : good
---
-module System.X509
-    ( getSystemCertificateStore
-    ) where
+module System.X509 (
+    getSystemCertificateStore,
+) where
 
 #if defined(WINDOWS)
 import System.X509.Win32
diff --git a/System/X509/Common.hs b/System/X509/Common.hs
new file mode 100644
--- /dev/null
+++ b/System/X509/Common.hs
@@ -0,0 +1,26 @@
+module System.X509.Common (
+    maybeSSLCertEnvOr,
+)
+where
+
+import Data.Foldable (asum)
+import Data.Maybe (catMaybes, fromMaybe)
+import Data.Monoid (mconcat)
+import Data.X509.CertificateStore
+import System.Environment (lookupEnv)
+
+getOpenSslEnvs :: IO (Maybe String)
+getOpenSslEnvs =
+    asum
+        <$> traverse
+            lookupEnv
+            [ "SSL_CERT_FILE"
+            , "SSL_CERT_DIR"
+            ]
+
+maybeSSLCertEnvOr :: IO CertificateStore -> IO CertificateStore
+maybeSSLCertEnvOr defaultStore = do
+    overrideCertPaths <- getOpenSslEnvs
+    case overrideCertPaths of
+        Nothing -> defaultStore
+        Just certPath -> fromMaybe mempty <$> (readCertificateStore certPath)
diff --git a/System/X509/MacOS.hs b/System/X509/MacOS.hs
--- a/System/X509/MacOS.hs
+++ b/System/X509/MacOS.hs
@@ -1,15 +1,16 @@
-module System.X509.MacOS
-    ( getSystemCertificateStore
-    ) where
+module System.X509.MacOS (
+    getSystemCertificateStore,
+) where
 
-import Data.PEM (pemParseLBS, PEM(..))
-import System.Process
-import qualified Data.ByteString.Lazy as LBS
 import Control.Applicative
+import qualified Data.ByteString.Lazy as LBS
 import Data.Either
+import Data.PEM (PEM (..), pemParseLBS)
+import System.Process
 
 import Data.X509
 import Data.X509.CertificateStore
+import System.X509.Common (maybeSSLCertEnvOr)
 
 rootCAKeyChain :: FilePath
 rootCAKeyChain = "/System/Library/Keychains/SystemRootCertificates.keychain"
@@ -19,11 +20,20 @@
 
 listInKeyChains :: [FilePath] -> IO [SignedCertificate]
 listInKeyChains keyChains = do
-    (_, Just hout, _, ph) <- createProcess (proc "security" ("find-certificate" : "-pa" : keyChains)) { std_out = CreatePipe }
+    (_, Just hout, _, ph) <-
+        createProcess
+            (proc "security" ("find-certificate" : "-pa" : keyChains))
+                { std_out = CreatePipe
+                }
     pems <- either error id . pemParseLBS <$> LBS.hGetContents hout
-    let targets = rights $ map (decodeSignedCertificate . pemContent) $ filter ((=="CERTIFICATE") . pemName) pems
+    let targets =
+            rights $
+                map (decodeSignedCertificate . pemContent) $
+                    filter ((== "CERTIFICATE") . pemName) pems
     _ <- targets `seq` waitForProcess ph
     return targets
 
 getSystemCertificateStore :: IO CertificateStore
-getSystemCertificateStore = makeCertificateStore <$> listInKeyChains [rootCAKeyChain, systemKeyChain]
+getSystemCertificateStore =
+    maybeSSLCertEnvOr
+        (makeCertificateStore <$> listInKeyChains [rootCAKeyChain, systemKeyChain])
diff --git a/System/X509/Unix.hs b/System/X509/Unix.hs
--- a/System/X509/Unix.hs
+++ b/System/X509/Unix.hs
@@ -11,13 +11,13 @@
 -- the path can be dynamically override using the environment variable
 -- defined by envPathOverride in the module, which by
 -- default is SYSTEM_CERTIFICATE_PATH
---
-module System.X509.Unix
-    ( getSystemCertificateStore
-    ) where
+module System.X509.Unix (
+    getSystemCertificateStore,
+) where
 
-import System.Environment (getEnv)
 import Data.X509.CertificateStore
+import System.Environment (getEnv)
+import System.X509.Common (maybeSSLCertEnvOr)
 
 import Control.Applicative ((<$>))
 import qualified Control.Exception as E
@@ -27,20 +27,23 @@
 
 defaultSystemPaths :: [FilePath]
 defaultSystemPaths =
-    [ "/etc/ssl/certs/"                 -- linux
-    , "/system/etc/security/cacerts/"   -- android
-    , "/usr/local/share/certs/"         -- freebsd
-    , "/etc/ssl/cert.pem"               -- openbsd
+    [ "/etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem" -- fedora
+    , "/etc/ssl/certs/" -- linux
+    , "/system/etc/security/cacerts/" -- android
+    , "/usr/local/share/certs/" -- freebsd
+    , "/etc/ssl/cert.pem" -- openbsd
     ]
 
 envPathOverride :: String
 envPathOverride = "SYSTEM_CERTIFICATE_PATH"
 
 getSystemCertificateStore :: IO CertificateStore
-getSystemCertificateStore = mconcat . catMaybes <$> (getSystemPaths >>= mapM readCertificateStore)
+getSystemCertificateStore =
+    maybeSSLCertEnvOr
+        (mconcat . catMaybes <$> (getSystemPaths >>= mapM readCertificateStore))
 
 getSystemPaths :: IO [FilePath]
-getSystemPaths = E.catch ((:[]) <$> getEnv envPathOverride) inDefault
-    where
-        inDefault :: E.IOException -> IO [FilePath]
-        inDefault _ = return defaultSystemPaths
+getSystemPaths = E.catch ((: []) <$> getEnv envPathOverride) inDefault
+  where
+    inDefault :: E.IOException -> IO [FilePath]
+    inDefault _ = return defaultSystemPaths
diff --git a/System/X509/Win32.hs b/System/X509/Win32.hs
--- a/System/X509/Win32.hs
+++ b/System/X509/Win32.hs
@@ -1,25 +1,27 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE ForeignFunctionInterface #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE CPP #-}
-module System.X509.Win32
-    ( getSystemCertificateStore
-    ) where
 
+module System.X509.Win32 (
+    getSystemCertificateStore,
+) where
+
+import Data.Word
 import Foreign.Ptr
 import Foreign.Storable
-import Data.Word
 
-import Control.Monad (when)
 import Control.Applicative
 import Control.Exception (catch)
+import Control.Monad (when)
 
 import qualified Data.ByteString.Internal as B
 
+import Data.ASN1.Error
 import Data.X509
 import Data.X509.CertificateStore
-import Data.ASN1.Error
 
 import System.Win32.Types
+import System.X509.Common (maybeSSLCertEnvOr)
 
 type HCertStore = Ptr Word8
 type PCCERT_Context = Ptr Word8
@@ -30,7 +32,8 @@
     c_CertCloseStore :: HCertStore -> DWORD -> IO ()
 
 foreign import stdcall unsafe "CertEnumCertificatesInStore"
-    c_CertEnumCertificatesInStore :: HCertStore -> PCCERT_Context -> IO PCCERT_Context
+    c_CertEnumCertificatesInStore
+        :: HCertStore -> PCCERT_Context -> IO PCCERT_Context
 
 certOpenSystemStore :: IO HCertStore
 certOpenSystemStore = withTString "ROOT" $ \cstr ->
@@ -38,32 +41,35 @@
 
 certFromContext :: PCCERT_Context -> IO (Either String SignedCertificate)
 certFromContext cctx = do
-    ty  <- peek (castPtr cctx :: Ptr DWORD)
-    p   <- peek (castPtr (cctx `plusPtr` pbCertEncodedPos) :: Ptr (Ptr BYTE))
+    ty <- peek (castPtr cctx :: Ptr DWORD)
+    p <- peek (castPtr (cctx `plusPtr` pbCertEncodedPos) :: Ptr (Ptr BYTE))
     len <- peek (castPtr (cctx `plusPtr` cbCertEncodedPos) :: Ptr DWORD)
     process ty p len
-  where process 1 p len = do
-            b <- B.create (fromIntegral len) $ \dst -> B.memcpy dst p (fromIntegral len)
-            return $ decodeSignedObject b
-        process ty _ _ =
-            return $ Left ("windows certificate store: not supported type: " ++ show ty)
-        pbCertEncodedPos = alignment (undefined :: Ptr (Ptr BYTE))
-        cbCertEncodedPos = pbCertEncodedPos + sizeOf (undefined :: Ptr (Ptr BYTE))
+  where
+    process 1 p len = do
+        b <- B.create (fromIntegral len) $ \dst -> B.memcpy dst p (fromIntegral len)
+        return $ decodeSignedObject b
+    process ty _ _ =
+        return $ Left ("windows certificate store: not supported type: " ++ show ty)
+    pbCertEncodedPos = alignment (undefined :: Ptr (Ptr BYTE))
+    cbCertEncodedPos = pbCertEncodedPos + sizeOf (undefined :: Ptr (Ptr BYTE))
 
 getSystemCertificateStore :: IO CertificateStore
-getSystemCertificateStore = do
+getSystemCertificateStore = maybeSSLCertEnvOr $ do
     store <- certOpenSystemStore
     when (store == nullPtr) $ error "no store"
     certs <- loop store nullPtr
     c_CertCloseStore store 0
     return (makeCertificateStore certs)
-  where loop st ptr = do
-            r <- c_CertEnumCertificatesInStore st ptr
-            if r == nullPtr
-                then return []
-                else do
+  where
+    loop st ptr = do
+        r <- c_CertEnumCertificatesInStore st ptr
+        if r == nullPtr
+            then return []
+            else
+                do
                     ecert <- certFromContext r
                     case ecert of
-                        Left _     -> loop st r
+                        Left _ -> loop st r
                         Right cert -> (cert :) <$> (loop st r)
                     `catch` \(_ :: ASN1Error) -> loop st r
diff --git a/crypton-x509-system.cabal b/crypton-x509-system.cabal
--- a/crypton-x509-system.cabal
+++ b/crypton-x509-system.cabal
@@ -1,43 +1,54 @@
-Name:                crypton-x509-system
-version:             1.6.7
-Synopsis:            Handle per-operating-system X.509 accessors and storage
-Description:         System X.509 handling for accessing operating system dependents store and other storage methods
-License:             BSD3
-License-file:        LICENSE
-Copyright:           Vincent Hanquez <vincent@snarc.org>
-Author:              Vincent Hanquez <vincent@snarc.org>
-Maintainer:          Kazu Yamamoto <kazu@iij.ad.jp>
-Build-Type:          Simple
-Category:            Data
-stability:           experimental
-Homepage:            https://github.com/kazu-yamamoto/crypton-certificate
-Cabal-Version:       >= 1.10
+cabal-version:      >=1.10
+name:               crypton-x509-system
+version:            1.6.8
+license:            BSD3
+license-file:       LICENSE
+copyright:          Vincent Hanquez <vincent@snarc.org>
+maintainer:         Kazu Yamamoto <kazu@iij.ad.jp>
+author:             Vincent Hanquez <vincent@snarc.org>
+stability:          experimental
+homepage:           https://github.com/kazu-yamamoto/crypton-certificate
+synopsis:           Handle per-operating-system X.509 accessors and storage
+description:
+    System X.509 handling for accessing operating system dependents store and other storage methods
 
-Library
-  Default-Language:  Haskell2010
-  Build-Depends:     base >= 3 && < 5
-                   , bytestring
-                   , mtl
-                   , containers
-                   , directory
-                   , filepath
-                   , process
-                   , pem >= 0.1 && < 0.3
-                   , crypton-x509 >= 1.6
-                   , crypton-x509-store >= 1.6.2
-  Exposed-modules:   System.X509
-                     System.X509.Unix
-                     System.X509.MacOS
-  ghc-options:       -Wall
-  if os(windows)
-     cpp-options:     -DWINDOWS
-     Build-Depends:   Win32, asn1-encoding
-     extra-libraries: Crypt32
-     Exposed-modules: System.X509.Win32
-  if os(OSX)
-     cpp-options: -DMACOSX
+category:           Data
+build-type:         Simple
+extra-source-files: ChangeLog.md
 
 source-repository head
-  type:     git
-  location: https://github.com/kazu-yamamoto/crypton-certificate
-  subdir:   x509-system
+    type:     git
+    location: https://github.com/kazu-yamamoto/crypton-certificate
+    subdir:   x509-system
+
+library
+    exposed-modules:
+        System.X509
+        System.X509.Common
+        System.X509.Unix
+        System.X509.MacOS
+
+    default-language: Haskell2010
+    ghc-options:      -Wall
+    build-depends:
+        base >=3 && <5,
+        bytestring,
+        mtl,
+        containers,
+        directory,
+        filepath,
+        process,
+        pem >=0.1 && <0.3,
+        crypton-x509 >=1.6,
+        crypton-x509-store >=1.6.2
+
+    if os(windows)
+        exposed-modules: System.X509.Win32
+        cpp-options:     -DWINDOWS
+        extra-libraries: Crypt32
+        build-depends:
+            Win32,
+            asn1-encoding
+
+    if os(osx)
+        cpp-options: -DMACOSX
