diff --git a/pkgs/development/beam-modules/build-mix.nix b/pkgs/development/beam-modules/build-mix.nix
index ed286c4c2bd1..dd2d3f7dea97 100644
--- a/pkgs/development/beam-modules/build-mix.nix
+++ b/pkgs/development/beam-modules/build-mix.nix
@@ -57,7 +57,8 @@ let
           in
           "[${lib.concatStringsSep "," options}]";
 
-        LC_ALL = "C.UTF-8";
+        LANG = if stdenv.isLinux then "C.UTF-8" else "C";
+        LC_CTYPE = if stdenv.isLinux then "C.UTF-8" else "UTF-8";
 
         # add to ERL_LIBS so other modules can find at runtime.
         # http://erlang.org/doc/man/code.html#code-path
diff --git a/pkgs/development/beam-modules/mix-release.nix b/pkgs/development/beam-modules/mix-release.nix
index 5c5f833119aa..986ff9843864 100644
--- a/pkgs/development/beam-modules/mix-release.nix
+++ b/pkgs/development/beam-modules/mix-release.nix
@@ -134,7 +134,8 @@ stdenv.mkDerivation (
       in
       "[${lib.concatStringsSep "," options}]";
 
-    LC_ALL = "C.UTF-8";
+    LANG = if stdenv.isLinux then "C.UTF-8" else "C";
+    LC_CTYPE = if stdenv.isLinux then "C.UTF-8" else "UTF-8";
 
     postUnpack =
       ''