diff --git a/init.el b/init.el
index 76bd5ea..435d97c 100644
--- a/init.el
+++ b/init.el
@@ -133,6 +133,7 @@ PACKAGE is installed and the current version is deleted."
             elscreen          ; window session manager
             expand-region     ; Increase selected region by semantic units
             flx-ido           ; flx integration for ido
+            idle-require      ; load elisp libraries while Emacs is idle
             ido-vertical-mode ; Makes ido-mode display vertically.
             geiser            ; GNU Emacs and Scheme talk to each other
             haskell-mode      ; A Haskell editing mode
@@ -754,9 +755,6 @@ the languages in ISPELL-LANGUAGES when invoked."
 (defun c-setup ()
   (local-set-key (kbd "C-c C-c") 'compile))
 
-(require 'auto-complete-c-headers)
-(add-to-list 'ac-sources 'ac-source-c-headers)
-
 (add-hook 'c-mode-common-hook 'c-setup)
 
 ;; Some statements in Java appear often, and become tedious to write
diff --git a/init.org b/init.org
index 74aa1d4..e31c9e2 100644
--- a/init.org
+++ b/init.org
@@ -165,6 +165,7 @@
                  elscreen          ; window session manager
                  expand-region     ; Increase selected region by semantic units
                  flx-ido           ; flx integration for ido
+                 idle-require      ; load elisp libraries while Emacs is idle
                  ido-vertical-mode ; Makes ido-mode display vertically.
                  geiser            ; GNU Emacs and Scheme talk to each other
                  haskell-mode      ; A Haskell editing mode
@@ -908,9 +909,6 @@
    (defun c-setup ()
      (local-set-key (kbd "C-c C-c") 'compile))
 
-   (require 'auto-complete-c-headers)
-   (add-to-list 'ac-sources 'ac-source-c-headers)
-
    (add-hook 'c-mode-common-hook 'c-setup)
    #+END_SRC