diff --git a/pkgs/development/tools/parsing/alex/3.1.0.nix b/pkgs/development/tools/parsing/alex/3.1.0.nix
new file mode 100644
index 000000000000..b6d46bea58e7
--- /dev/null
+++ b/pkgs/development/tools/parsing/alex/3.1.0.nix
@@ -0,0 +1,18 @@
+{ cabal, perl, QuickCheck }:
+
+cabal.mkDerivation (self: {
+  pname = "alex";
+  version = "3.1.0";
+  sha256 = "1d2kdn4g3zyc3ijiscbqayzg1apy0iih603dv90pr9w2f36djrkh";
+  isLibrary = false;
+  isExecutable = true;
+  buildDepends = [ QuickCheck ];
+  buildTools = [ perl ];
+  meta = {
+    homepage = "http://www.haskell.org/alex/";
+    description = "Alex is a tool for generating lexical analysers in Haskell";
+    license = self.stdenv.lib.licenses.bsd3;
+    platforms = self.ghc.meta.platforms;
+    maintainers = [ self.stdenv.lib.maintainers.andres ];
+  };
+})
diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index 3f50e4ae5cf0..49aa41c7601b 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -174,7 +174,7 @@ let result = let callPackage = x : y : modifyPrio (newScope result.finalReturn x
     xhtml        = self.xhtml_3000_2_1;
     zlib         = self.zlib_0_5_4_1;
     cabalInstall = self.cabalInstall_1_18_0_1;
-    alex         = self.alex_3_0_5;
+    alex         = self.alex_3_1_0;
     haddock      = self.haddock_2_13_2;
     happy        = self.happy_1_18_11;
     primitive    = self.primitive_0_5_0_1;      # semi-official, but specified
@@ -2332,7 +2332,8 @@ let result = let callPackage = x : y : modifyPrio (newScope result.finalReturn x
   alex_3_0_1 = callPackage ../development/tools/parsing/alex/3.0.1.nix {};
   alex_3_0_2 = callPackage ../development/tools/parsing/alex/3.0.2.nix {};
   alex_3_0_5 = callPackage ../development/tools/parsing/alex/3.0.5.nix {};
-  alex = self.alex_3_0_5;
+  alex_3_1_0 = callPackage ../development/tools/parsing/alex/3.1.0.nix {};
+  alex = self.alex_3_1_0;
 
   alexMeta = callPackage ../development/tools/haskell/alex-meta {};