diff --git a/modules/environment/default.nix b/modules/environment/default.nix
index 3d349868..fdc942c9 100644
--- a/modules/environment/default.nix
+++ b/modules/environment/default.nix
@@ -33,13 +33,26 @@ in {
 
     environment.systemPath = mkOption {
       type = types.loeOf types.path;
-      default = [ "$HOME/.nix-profile" "/run/current-system/sw" "/nix/var/nix/profiles/default" "/usr/local" ];
+      default = (reverseList cfg.profiles) ++ [ "/usr/local" "/usr" "" ];
       description = ''
         The set of paths that are added to PATH
       '';
       apply = x: if isList x then makeBinPath x else x;
     };
 
+    environment.profiles = mkOption {
+      type = types.listOf types.path;
+      default =
+        [ # Use user, default and system profiles.
+          "$HOME/.nix-profile"
+          "/nix/var/nix/profiles/default"
+          "/run/current-system/sw"
+        ];
+      description = ''
+        A list of profiles used to setup the global environment.
+      '';
+    };
+
     environment.extraOutputsToInstall = mkOption {
       type = types.listOf types.str;
       default = [ ];
@@ -82,6 +95,16 @@ in {
       '';
     };
 
+    environment.interactiveShellInit = mkOption {
+      default = "";
+      description = ''
+        Shell script code called during interactive shell initialisation.
+        This code is asumed to be shell-independent, which means you should
+        stick to pure sh without sh word split.
+      '';
+      type = types.lines;
+    };
+
   };
 
   config = {
@@ -95,5 +118,18 @@ in {
       inherit (cfg) extraOutputsToInstall;
     };
 
+    environment.extraInit = ''
+       # reset TERM with new TERMINFO available (if any)
+       export TERM=$TERM
+
+       export NIX_USER_PROFILE_DIR="/nix/var/nix/profiles/per-user/$USER"
+       export NIX_PROFILES="${concatStringsSep " " (reverseList cfg.profiles)}"
+    '';
+
+    environment.variables =
+      { EDITOR = mkDefault "nano";
+        PAGER = mkDefault "less -R";
+      };
+
   };
 }
diff --git a/modules/programs/bash.nix b/modules/programs/bash.nix
index ae8e399c..2231401b 100644
--- a/modules/programs/bash.nix
+++ b/modules/programs/bash.nix
@@ -15,6 +15,17 @@ let
       makeWrapper ${pkgs.bash}/bin/bash $out/bin/bash
     '';
 
+
+  interactiveShellInit = ''
+    export PATH=${config.environment.systemPath}''${PATH:+:$PATH}
+    ${config.system.build.setEnvironment}
+    ${config.system.build.setAliases}
+
+    ${config.environment.extraInit}
+    ${config.environment.interactiveShellInit}
+    ${cfg.interactiveShellInit}
+  '';
+
 in
 
 {
@@ -53,7 +64,7 @@ in
         pkgs.bash
       ];
 
-    environment.variables.SHELL = "${cfg.shell}";
+    environment.variables.SHELL = mkDefault "${cfg.shell}";
 
     environment.etc."bashrc".text = ''
       # /etc/bashrc: DO NOT EDIT -- this file has been generated automatically.
@@ -63,12 +74,7 @@ in
       if [ -n "$__ETC_BASHRC_SOURCED" -o -n "$NOSYSBASHRC" ]; then return; fi
       __ETC_BASHRC_SOURCED=1
 
-      export PATH=${config.environment.systemPath}''${PATH:+:$PATH}
-      ${config.system.build.setEnvironment}
-      ${config.system.build.setAliases}
-
-      ${cfg.interactiveShellInit}
-      ${config.environment.extraInit}
+      ${interactiveShellInit}
 
       # Read system-wide modifications.
       if test -f /etc/bash.local; then
diff --git a/modules/programs/zsh.nix b/modules/programs/zsh.nix
index c91b5211..1990e4d1 100644
--- a/modules/programs/zsh.nix
+++ b/modules/programs/zsh.nix
@@ -15,6 +15,33 @@ let
       makeWrapper ${pkgs.zsh}/bin/zsh $out/bin/zsh
     '';
 
+  interactiveShellInit = ''
+    # history defaults
+    SAVEHIST=2000
+    HISTSIZE=2000
+    HISTFILE=$HOME/.zsh_history
+
+    setopt HIST_IGNORE_DUPS SHARE_HISTORY HIST_FCNTL_LOCK
+
+    export PATH=${config.environment.systemPath}''${PATH:+:$PATH}
+    ${config.system.build.setEnvironment}
+    ${config.system.build.setAliases}
+
+    ${config.environment.extraInit}
+    ${config.environment.interactiveShellInit}
+
+    ${cfg.interactiveShellInit}
+    ${cfg.promptInit}
+
+    # Tell zsh how to find installed completions
+    for p in ''${(z)NIX_PROFILES}; do
+      fpath+=($p/share/zsh/site-functions $p/share/zsh/$ZSH_VERSION/functions)
+    done
+
+    ${optionalString cfg.enableCompletion "autoload -U compinit && compinit"}
+    ${optionalString cfg.enableBashCompletion "autoload -U bashcompinit && bashcompinit"}
+  '';
+
 in
 
 {
@@ -93,7 +120,7 @@ in
         pkgs.zsh
       ];
 
-    environment.variables.SHELL = "${cfg.shell}";
+    environment.variables.SHELL = mkDefault "${cfg.shell}";
 
     environment.etc."zshenv".text = ''
       # /etc/zshenv: DO NOT EDIT -- this file has been generated automatically.
@@ -136,17 +163,7 @@ in
       if [ -n "$__ETC_ZSHRC_SOURCED" -o -n "$NOSYSZSHRC" ]; then return; fi
       __ETC_ZSHRC_SOURCED=1
 
-      export PATH=${config.environment.systemPath}''${PATH:+:$PATH}
-      ${config.system.build.setEnvironment}
-      ${config.system.build.setAliases}
-
-      ${cfg.interactiveShellInit}
-
-      ${cfg.promptInit}
-      ${optionalString cfg.enableCompletion "autoload -U compinit && compinit"}
-      ${optionalString cfg.enableBashCompletion "autoload -U bashcompinit && bashcompinit"}
-
-      ${config.environment.extraInit}
+      ${interactiveShellInit}
 
       # Read system-wide modifications.
       if test -f /etc/zshrc.local; then