diff --git a/pkgs/development/libraries/haskell/base64-bytestring/0.1.0.3.nix b/pkgs/development/libraries/haskell/base64-bytestring/0.1.0.3.nix
new file mode 100644
index 00000000000..f974a72347f
--- /dev/null
+++ b/pkgs/development/libraries/haskell/base64-bytestring/0.1.0.3.nix
@@ -0,0 +1,17 @@
+{ cabal }:
+
+cabal.mkDerivation (self: {
+  pname = "base64-bytestring";
+  version = "0.1.0.3";
+  sha256 = "0d4j8b1d8z9qr1y446bfkj764xgilk8gw2frj0wn0717y8knvmx3";
+  meta = {
+    homepage = "https://github.com/bos/base64-bytestring";
+    description = "Fast base64 encoding and deconding for ByteStrings";
+    license = self.stdenv.lib.licenses.bsd3;
+    platforms = self.ghc.meta.platforms;
+    maintainers = [
+      self.stdenv.lib.maintainers.andres
+      self.stdenv.lib.maintainers.simons
+    ];
+  };
+})
diff --git a/pkgs/development/libraries/haskell/base64-bytestring/default.nix b/pkgs/development/libraries/haskell/base64-bytestring/0.1.1.0.nix
similarity index 100%
rename from pkgs/development/libraries/haskell/base64-bytestring/default.nix
rename to pkgs/development/libraries/haskell/base64-bytestring/0.1.1.0.nix
diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index 90fd84573b1..534cc3aa2f7 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -456,7 +456,9 @@ let result = let callPackage = x : y : modifyPrio (newScope result.final x y);
 
   base64String = callPackage ../development/libraries/haskell/base64-string {};
 
-  base64Bytestring = callPackage ../development/libraries/haskell/base64-bytestring {};
+  base64Bytestring_0_1_0_3 = callPackage ../development/libraries/haskell/base64-bytestring/0.1.0.3.nix {};
+  base64Bytestring_0_1_1_0 = callPackage ../development/libraries/haskell/base64-bytestring/0.1.1.0.nix {};
+  base64Bytestring = self.base64Bytestring_0_1_0_3; # Version 0.1.1.0 has serious performance issues.
 
   baseUnicodeSymbols = callPackage ../development/libraries/haskell/base-unicode-symbols {};