diff --git a/modules/environment/default.nix b/modules/environment/default.nix
index 3b97a3ec..00d58c09 100644
--- a/modules/environment/default.nix
+++ b/modules/environment/default.nix
@@ -16,6 +16,10 @@ let
 in
 
 {
+  imports = [
+    (mkRenamedOptionModule ["environment" "postBuild"] ["environment" "extraSetup"])
+  ];
+
   options = {
     environment.systemPackages = mkOption {
       type = types.listOf types.package;
@@ -43,12 +47,6 @@ in
       description = "A list of profiles used to setup the global environment.";
     };
 
-    environment.postBuild = mkOption {
-      type = types.lines;
-      default = "";
-      description = "Commands to execute when building the global environment.";
-    };
-
     environment.extraOutputsToInstall = mkOption {
       type = types.listOf types.str;
       default = [];
@@ -147,6 +145,17 @@ in
       '';
       type = types.lines;
     };
+
+    environment.extraSetup = mkOption {
+      type = types.lines;
+      default = "";
+      description = ''
+        Shell fragments to be run after the system environment has been created.
+        This should only be used for things that need to modify the internals
+        of the environment, e.g. generating MIME caches.
+        The environment being built can be accessed at $out.
+      '';
+    };
   };
 
   config = {
@@ -188,7 +197,8 @@ in
     system.path = pkgs.buildEnv {
       name = "system-path";
       paths = cfg.systemPackages;
-      inherit (cfg) postBuild pathsToLink extraOutputsToInstall;
+      postBuild = cfg.extraSetup;
+      inherit (cfg) pathsToLink extraOutputsToInstall;
     };
 
     system.build.setEnvironment = pkgs.writeText "set-environment" ''
@@ -205,6 +215,5 @@ in
     system.build.setAliases = pkgs.writeText "set-aliases" ''
       ${concatStringsSep "\n" aliasCommands}
     '';
-
   };
 }
diff --git a/modules/programs/info/default.nix b/modules/programs/info/default.nix
index cf857d9f..d70e3770 100644
--- a/modules/programs/info/default.nix
+++ b/modules/programs/info/default.nix
@@ -22,7 +22,7 @@ in
     environment.pathsToLink = [ "/info" "/share/info" ];
     environment.extraOutputsToInstall = [ "info" ];
 
-    environment.postBuild = ''
+    environment.extraSetup = ''
       if test -w $out/share/info; then
         shopt -s nullglob
         for i in $out/share/info/*.info $out/share/info/*.info.gz; do