diff --git a/pkgs/development/beam-modules/build-mix.nix b/pkgs/development/beam-modules/build-mix.nix
index 52c0ce1ad1f8..1994f89f3ef1 100644
--- a/pkgs/development/beam-modules/build-mix.nix
+++ b/pkgs/development/beam-modules/build-mix.nix
@@ -57,7 +57,8 @@ lib.extendMkDerivation {
 
         # some hooks need name-version, but we've overridden name above for the nix package
         beamModuleName = args.name;
-      };
+      }
+      // (args.env or { });
 
       __darwinAllowLocalNetworking = true;
 
diff --git a/pkgs/development/beam-modules/build-rebar3.nix b/pkgs/development/beam-modules/build-rebar3.nix
index 11b1c8b44e52..1145905996bc 100644
--- a/pkgs/development/beam-modules/build-rebar3.nix
+++ b/pkgs/development/beam-modules/build-rebar3.nix
@@ -67,7 +67,8 @@ lib.extendMkDerivation {
           "[${lib.concatStringsSep "," options}]";
 
         beamModuleName = args.name;
-      };
+      }
+      // (args.env or { });
 
       setupHook = writeText "setupHook.sh" ''
         addToSearchPath ERL_LIBS "$1/lib/erlang/lib/"