diff --git a/config.nix b/config.nix
index 841ce4ab..1cccbb79 100644
--- a/config.nix
+++ b/config.nix
@@ -36,7 +36,7 @@ let
           pkgs.nox
         ];
 
-      launchd.agents.activate-system =
+      launchd.daemons.activate-system =
         { serviceConfig.Program = "${config.system.build.activate}";
           serviceConfig.RunAtLoad = true;
         };
@@ -144,7 +144,7 @@ let
         if [ -n "$__ETC_ZSHENV_SOURCED" ]; then return; fi
         export __ETC_ZSHENV_SOURCED=1
 
-        export NIX_PATH=nixpkgs=$HOME/.nix-defexpr/nixpkgs:$NIX_PATH/.nix-defexpr/channels_root
+        export NIX_PATH=nixpkgs=$HOME/.nix-defexpr/nixpkgs:$HOME/.nix-defexpr/channels_root
 
         # Set up secure multi-user builds: non-root users build through the
         # Nix daemon.
diff --git a/modules/launchd/default.nix b/modules/launchd/default.nix
index 5d1fc699..b692e744 100644
--- a/modules/launchd/default.nix
+++ b/modules/launchd/default.nix
@@ -44,13 +44,33 @@ in
     launchd.agents = mkOption {
       default = {};
       type = types.attrsOf (types.submodule serviceOptions);
-      description = "Definition of launchd agents.";
+      description = ''
+        Definition of per-user launchd agents.
+
+        When a user logs in, a per-user launchd is started.
+        It does the following:
+        1. It loads the parameters for each launch-on-demand user agent from the property list files found in /System/Library/LaunchAgents, /Library/LaunchAgents, and the user’s individual Library/LaunchAgents directory.
+        2. It registers the sockets and file descriptors requested by those user agents.
+        3. It launches any user agents that requested to be running all the time.
+        4. As requests for a particular service arrive, it launches the corresponding user agent and passes the request to it.
+        5. When the user logs out, it sends a SIGTERM signal to all of the user agents that it started.
+      '';
     };
 
     launchd.daemons = mkOption {
       default = {};
       type = types.attrsOf (types.submodule serviceOptions);
-      description = "Definition of launchd daemons.";
+      description = ''
+        Definition of launchd daemons.
+
+        After the system is booted and the kernel is running, launchd is run to finish the system initialization.
+        As part of that initialization, it goes through the following steps:
+        1. It loads the parameters for each launch-on-demand system-level daemon from the property list files found in /System/Library/LaunchDaemons/ and /Library/LaunchDaemons/.
+        2. It registers the sockets and file descriptors requested by those daemons.
+        3. It launches any daemons that requested to be running all the time.
+        4. As requests for a particular service arrive, it launches the corresponding daemon and passes the request to it.
+        5. When the system shuts down, it sends a SIGTERM signal to all of the daemons that it started.
+      '';
     };
 
   };
diff --git a/modules/system/activation-scripts.nix b/modules/system/activation-scripts.nix
index f32e1dee..fe3131d3 100644
--- a/modules/system/activation-scripts.nix
+++ b/modules/system/activation-scripts.nix
@@ -34,7 +34,7 @@ in
 
   config = {
 
-    system.build.activate = pkgs.writeText "activate-system" ''
+    system.build.activate = pkgs.writeScript "activate-system" ''
       #! ${pkgs.stdenv.shell}
 
       # Make this configuration the current configuration.