diff --git a/home-manager/install.nix b/home-manager/install.nix
index c6d3aa4e4..be9f17df0 100644
--- a/home-manager/install.nix
+++ b/home-manager/install.nix
@@ -4,6 +4,8 @@ pkgs.runCommand
   "home-manager-install"
   {
     propagatedBuildInputs = [ home-manager ];
+    preferLocalBuild = true;
+    allowSubstitutes = false;
     shellHook = ''
       echo
       echo "Creating initial Home Manager generation..."
diff --git a/modules/files.nix b/modules/files.nix
index fd58027b3..a9b8740db 100644
--- a/modules/files.nix
+++ b/modules/files.nix
@@ -220,6 +220,9 @@ in
 
       nativeBuildInputs = [ pkgs.xlibs.lndir ];
 
+      preferLocalBuild = true;
+      allowSubstitutes = false;
+
       # Symlink directories and files that have the right execute bit.
       # Copy files that need their execute bit changed.
       buildCommand = ''
diff --git a/modules/home-environment.nix b/modules/home-environment.nix
index ae0e4ad57..229e3d22f 100644
--- a/modules/home-environment.nix
+++ b/modules/home-environment.nix
@@ -349,6 +349,9 @@ in
         pkgs.stdenv.mkDerivation {
           name = "home-manager-generation";
 
+          preferLocalBuild = true;
+          allowSubstitutes = false;
+
           buildCommand = ''
             mkdir -p $out