diff --git a/init.el b/init.el
index 36847b9..d5ddba5 100644
--- a/init.el
+++ b/init.el
@@ -21,8 +21,9 @@ tangled, and the tangled file is compiled."
     (let* ((local-pkg-desc (or (assq package package-alist)
                                (assq package package--builtins)))
            (newest-pkg-desc (assq package package-archive-contents)))
-      (version-list-= (package-desc-vers (cdr local-pkg-desc))
-                      (package-desc-vers (cdr newest-pkg-desc))))))
+      (and local-pkg-desc newest-pkg-desc
+           (version-list-= (package-desc-vers (cdr local-pkg-desc))
+                           (package-desc-vers (cdr newest-pkg-desc)))))))
 
 (defun upgrade-or-install-package (package)
   "Unless the newest available version of PACKAGE is installed
@@ -356,7 +357,7 @@ LANGUAGES (cyclic) list."
   (when (executable-find ispell-program-name)
     ad-do-it))
 
-(dolist (mode '(slime-repl-mode inferior-lisp-mode inferior-scheme-mode))
+(dolist (mode '(slime-repl-mode geiser-repl-mode))
   (add-to-list 'pretty-lambda-auto-modes mode))
 
 (pretty-lambda-for-modes)
@@ -383,6 +384,7 @@ LANGUAGES (cyclic) list."
 (add-hook 'geiser-repl-mode-hook 'ac-geiser-setup)
 (eval-after-load "auto-complete"
   '(add-to-list 'ac-modes 'geiser-repl-mode))
+(setq geiser-active-implementations '(racket))
 
 (defun c-setup ()
   (local-set-key (kbd "C-c C-c") 'compile))
diff --git a/init.org b/init.org
index 984122a..c0cb63a 100644
--- a/init.org
+++ b/init.org
@@ -62,8 +62,9 @@
          (let* ((local-pkg-desc (or (assq package package-alist)
                                     (assq package package--builtins)))
                 (newest-pkg-desc (assq package package-archive-contents)))
-           (version-list-= (package-desc-vers (cdr local-pkg-desc))
-                           (package-desc-vers (cdr newest-pkg-desc))))))
+           (and local-pkg-desc newest-pkg-desc
+                (version-list-= (package-desc-vers (cdr local-pkg-desc))
+                                (package-desc-vers (cdr newest-pkg-desc)))))))
    #+END_SRC
 
    Let's write a function to install a package if it is not installed or
@@ -682,7 +683,7 @@
    function to activate =pretty-lambda-mode= in lisp modes.
 
    #+BEGIN_SRC emacs-lisp :tangle yes
-     (dolist (mode '(slime-repl-mode inferior-lisp-mode inferior-scheme-mode))
+     (dolist (mode '(slime-repl-mode geiser-repl-mode))
        (add-to-list 'pretty-lambda-auto-modes mode))
 
      (pretty-lambda-for-modes)
@@ -740,14 +741,15 @@
 *** Scheme
 
     [[http://www.nongnu.org/geiser/][Geiser]] provides features similar to Slime for Scheme editing. Everything
-    works pretty much out of the box, the only thing we need to add is the
-    auto completion.
+    works pretty much out of the box, we only need to add auto completion,
+    and specify which scheme-interpreter we prefer.
 
    #+BEGIN_SRC emacs-lisp :tangle yes
      (add-hook 'geiser-mode-hook 'ac-geiser-setup)
      (add-hook 'geiser-repl-mode-hook 'ac-geiser-setup)
      (eval-after-load "auto-complete"
        '(add-to-list 'ac-modes 'geiser-repl-mode))
+     (setq geiser-active-implementations '(racket))
    #+END_SRC
 
 ** Java and C
diff --git a/init.pdf b/init.pdf
index 7581652..98d5e68 100644
Binary files a/init.pdf and b/init.pdf differ