diff --git a/pkgs/development/beam-modules/default.nix b/pkgs/development/beam-modules/default.nix
index a1eedaad6a0f..63d046c7b47e 100644
--- a/pkgs/development/beam-modules/default.nix
+++ b/pkgs/development/beam-modules/default.nix
@@ -43,6 +43,11 @@ let
         # BEAM-based languages.
         elixir = elixir_1_7;
 
+        elixir_1_9 = lib.callElixir ../interpreters/elixir/1.9.nix {
+          inherit rebar erlang;
+          debugInfo = true;
+        };
+
         elixir_1_8 = lib.callElixir ../interpreters/elixir/1.8.nix {
           inherit rebar erlang;
           debugInfo = true;
@@ -63,11 +68,6 @@ let
           debugInfo = true;
         };
 
-        elixir_1_4 = lib.callElixir ../interpreters/elixir/1.4.nix {
-          inherit rebar erlang;
-          debugInfo = true;
-        };
-
         # Remove old versions of elixir, when the supports fades out:
         #   https://hexdocs.pm/elixir/compatibility-and-deprecations.html
 
diff --git a/pkgs/development/interpreters/elixir/1.4.nix b/pkgs/development/interpreters/elixir/1.4.nix
deleted file mode 100644
index 9ddd9062acd9..000000000000
--- a/pkgs/development/interpreters/elixir/1.4.nix
+++ /dev/null
@@ -1,7 +0,0 @@
-{ mkDerivation }:
-
-mkDerivation rec {
-  version = "1.4.5";
-  sha256 = "18ivcxmh5bak13k3rjy7jjzin57rgb2nffhwnqb2wl7bpi8mrarw";
-  minimumOTPVersion = "18";
-}
diff --git a/pkgs/development/interpreters/elixir/1.9.nix b/pkgs/development/interpreters/elixir/1.9.nix
new file mode 100644
index 000000000000..622f2343c6e1
--- /dev/null
+++ b/pkgs/development/interpreters/elixir/1.9.nix
@@ -0,0 +1,7 @@
+{ mkDerivation }:
+
+mkDerivation rec {
+  version = "1.9.0";
+  sha256 = "0yfqh07wjgm10v6acn5pw8l8jndjly5kpzgw4harlj81wcaymlsw";
+  minimumOTPVersion = "20";
+}
diff --git a/pkgs/development/interpreters/elixir/generic-builder.nix b/pkgs/development/interpreters/elixir/generic-builder.nix
index 844d6eeb4fb9..b7e98af21097 100644
--- a/pkgs/development/interpreters/elixir/generic-builder.nix
+++ b/pkgs/development/interpreters/elixir/generic-builder.nix
@@ -22,10 +22,8 @@ in
 
     buildInputs = [ erlang rebar makeWrapper ];
 
-    LOCALE_ARCHIVE = stdenv.lib.optionalString stdenv.isLinux
-      "${pkgs.glibcLocales}/lib/locale/locale-archive";
-    LANG = "en_US.UTF-8";
-    LC_TYPE = "en_US.UTF-8";
+    LANG = "C.UTF-8";
+    LC_TYPE = "C.UTF-8";
 
     setupHook = ./setup-hook.sh;
 
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 9b09ef0d84ac..87efce6a995e 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -8278,7 +8278,7 @@ in
   inherit (beam.interpreters)
     erlang erlangR18 erlangR19 erlangR20 erlangR21 erlangR22
     erlang_odbc erlang_javac erlang_odbc_javac erlang_nox erlang_basho_R16B02
-    elixir elixir_1_8 elixir_1_7 elixir_1_6 elixir_1_5 elixir_1_4
+    elixir elixir_1_9 elixir_1_8 elixir_1_7 elixir_1_6 elixir_1_5
     lfe lfe_1_2;
 
   inherit (beam.packages.erlang)
diff --git a/pkgs/top-level/beam-packages.nix b/pkgs/top-level/beam-packages.nix
index 70a21c830f59..b1749b93ff0b 100644
--- a/pkgs/top-level/beam-packages.nix
+++ b/pkgs/top-level/beam-packages.nix
@@ -70,7 +70,7 @@ rec {
     # Other Beam languages. These are built with `beam.interpreters.erlang`. To
     # access for example elixir built with different version of Erlang, use
     # `beam.packages.erlangR19.elixir`.
-    inherit (packages.erlang) elixir elixir_1_8 elixir_1_7 elixir_1_6 elixir_1_5 elixir_1_4;
+    inherit (packages.erlang) elixir elixir_1_9 elixir_1_8 elixir_1_7 elixir_1_6 elixir_1_5;
 
     inherit (packages.erlang) lfe lfe_1_2;
   };