diff --git a/default.nix b/default.nix
index 58faa2d..1ca66ce 100644
--- a/default.nix
+++ b/default.nix
@@ -1,5 +1,7 @@
 { # Package set to build the Emacs environment from
   emacsPackages
+  # Emacs package to use during build
+, emacs ? emacsPackages.emacs
   # You may override to use your version of `straight`
 , straight ? null
   # Your `init.el` file to use for discovering and installing packages
@@ -8,10 +10,13 @@
 , emacsArgs ? []
   # Additional files you wish to load prior to executing package discovery
   # Good place to place to call `advice-add` from
-, emacsLoadFiles ? [] }:
+, emacsLoadFiles ? []
+  # Abort processing if a package not found in `emacsPackages`
+  # Setting it to false will result in just skipping an unavailable package
+, abortOnNotFound ? false }:
 
 let
-  libstraight = epkgs.callPackage ./libstraight.nix { inherit epkgs; };
+  libstraight = epkgs.callPackage ./libstraight.nix { inherit abortOnNotFound epkgs emacs; };
   epkgs =
     if straight == null then
       emacsPackages.overrideScope' (self: super:
diff --git a/libstraight.nix b/libstraight.nix
index d65e0a3..eb48124 100644
--- a/libstraight.nix
+++ b/libstraight.nix
@@ -1,8 +1,9 @@
-{ lib, stdenv, epkgs, writeScript }:
+{ abortOnNotFound ? true,
+  lib, stdenv, epkgs, emacs, writeScript }:
 
 let
   inherit (builtins) filter trace;
-  inherit (lib) concatMapStringsSep escapeShellArgs importJSON flatten unique optionalString;
+  inherit (lib) concatMapStringsSep escapeShellArgs importJSON flatten unique optionalString warn;
 
   expandDependencies = packages:
     let
@@ -23,7 +24,7 @@ let
         else
           ln -snf $psrc $REPO/${pkg.ename}
         fi
-        ${optionalString (pkg.src.meta ? homepage) ''
+        ${optionalString ((pkg.src ? meta) && (pkg.src.meta ? homepage)) ''
           if [[ ! -d $REPO/${baseNameOf pkg.src.meta.homepage} ]]; then
             ln -snf $psrc $REPO/${baseNameOf pkg.src.meta.homepage}
           fi
@@ -39,11 +40,12 @@ let
       list = importJSON json;
     in map (x:
       if epkgs ? "${x}" then epkgs.${x}
-      else (trace "XXX no attribute found for use-package ${x}") null) list;
+      else if abortOnNotFound then abort "Package not available: ${x}"
+      else (warn "Package not available: ${x}") null) list;
 
   packagesJSON = { emacsInitFile, emacsLoadFiles, emacsArgs }: stdenv.mkDerivation {
     name = "emacs-straight-packages.json";
-    buildInputs = [ epkgs.emacs ];
+    buildInputs = [ emacs ];
     buildPhase = ":";
     installPhase = ''
       runHook preInstall
@@ -61,7 +63,7 @@ let
   emacsEnv = { emacsInitFile, emacsLoadFiles, emacsArgs }: { packages, straightDir }: stdenv.mkDerivation {
     name = "straight-emacs-env";
     buildPhase = ":";
-    buildInputs = [ epkgs.emacs ];
+    buildInputs = [ emacs ];
     installPhase = ''
       runHook preInstall
 
diff --git a/setup.el b/setup.el
index 3b2ff6c..e34c05b 100644
--- a/setup.el
+++ b/setup.el
@@ -9,11 +9,15 @@
                             (let ((pkg (if (listp recipe)
                                               (car recipe)
                                          recipe)))
-                              (message "straight-use-package %s %s; pkg=%s" recipe r pkg)
+                              (message "straight-use-package %s %s" recipe r)
                               (add-to-list 'nix-straight--packages pkg))))
     (advice-add 'straight-recipes-retrieve
                 :override (lambda (pkg)
                             (list)))
+    (advice-add 'straight-use-recipes
+                :override (lambda (&rest r)
+                            (message "straight-use-recipes %s" r)
+                            ))
 
     (load init-file nil nil t)
     (princ (if (null nix-straight--packages)