diff --git a/modules/misc/nix.nix b/modules/misc/nix.nix
index 785a7c04..e98df2e0 100644
--- a/modules/misc/nix.nix
+++ b/modules/misc/nix.nix
@@ -30,7 +30,7 @@ let
           toString v
         else if isString v then
           v
-        else if isCoercibleToString v then
+        else if isConvertibleWithToString v then
           toString v
         else
           abort "The nix conf value: ${toPretty { } v} can not be encoded";
diff --git a/modules/misc/nixpkgs.nix b/modules/misc/nixpkgs.nix
index 283fa348..42f6724c 100644
--- a/modules/misc/nixpkgs.nix
+++ b/modules/misc/nixpkgs.nix
@@ -129,7 +129,9 @@ in {
 
   config = {
     _module.args = {
-      pkgs = mkOverride modules.defaultPriority _pkgs;
+      # We use a no-op override to make sure that the option can be merged without evaluating
+      # `_pkgs`, see https://github.com/nix-community/home-manager/pull/993
+      pkgs = mkOverride modules.defaultOverridePriority _pkgs;
       pkgs_i686 =
         if _pkgs.stdenv.isLinux && _pkgs.stdenv.hostPlatform.isx86 then
           _pkgs.pkgsi686Linux