diff --git a/gnu/local.mk b/gnu/local.mk
index 97ca3eb720..0eb18f26c1 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -505,7 +505,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/calibre-drop-unrar.patch			\
   %D%/packages/patches/calibre-no-updates-dialog.patch		\
   %D%/packages/patches/cdparanoia-fpic.patch			\
-  %D%/packages/patches/chicken-CVE-2016-6830+CVE-2016-6831.patch	\
+  %D%/packages/patches/chicken-CVE-2017-6949.patch		\
   %D%/packages/patches/chmlib-inttypes.patch			\
   %D%/packages/patches/clang-libc-search-path.patch		\
   %D%/packages/patches/clang-3.8-libc-search-path.patch		\
diff --git a/gnu/packages/patches/chicken-CVE-2016-6830+CVE-2016-6831.patch b/gnu/packages/patches/chicken-CVE-2016-6830+CVE-2016-6831.patch
deleted file mode 100644
index 59decde0e9..0000000000
--- a/gnu/packages/patches/chicken-CVE-2016-6830+CVE-2016-6831.patch
+++ /dev/null
@@ -1,81 +0,0 @@
-diff -ur a/irregex-core.scm b/irregex-core.scm
---- a/irregex-core.scm	2016-09-11 19:03:00.000000000 -0400
-+++ b/irregex-core.scm	2017-01-01 22:24:08.000000000 -0500
-@@ -30,6 +30,8 @@
- 
- ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
- ;;;; History
-+;; 0.9.6: 2016/12/05 - fixed exponential memory use of + in compilation
-+;;                     of backtracking matcher.
- ;; 0.9.5: 2016/09/10 - fixed a bug in irregex-fold handling of bow
- ;; 0.9.4: 2015/12/14 - performance improvement for {n,m} matches
- ;; 0.9.3: 2014/07/01 - R7RS library
-@@ -3170,16 +3172,7 @@
-               ((sre-empty? (sre-sequence (cdr sre)))
-                (error "invalid sre: empty *" sre))
-               (else
--               (letrec
--                   ((body
--                     (lp (sre-sequence (cdr sre))
--                         n
--                         flags
--                         (lambda (cnk init src str i end matches fail)
--                           (body cnk init src str i end matches
--                                 (lambda ()
--                                   (next cnk init src str i end matches fail)
--                                   ))))))
-+               (let ((body (rec (list '+ (sre-sequence (cdr sre))))))
-                  (lambda (cnk init src str i end matches fail)
-                    (body cnk init src str i end matches
-                          (lambda ()
-@@ -3204,10 +3197,21 @@
-                          (lambda ()
-                            (body cnk init src str i end matches fail))))))))
-             ((+)
--             (lp (sre-sequence (cdr sre))
--                 n
--                 flags
--                 (rec (list '* (sre-sequence (cdr sre))))))
-+             (cond
-+              ((sre-empty? (sre-sequence (cdr sre)))
-+               (error "invalid sre: empty +" sre))
-+              (else
-+               (letrec
-+                   ((body
-+                     (lp (sre-sequence (cdr sre))
-+                         n
-+                         flags
-+                         (lambda (cnk init src str i end matches fail)
-+                           (body cnk init src str i end matches
-+                                 (lambda ()
-+                                   (next cnk init src str i end matches fail)
-+                                   ))))))
-+                 body))))
-             ((=)
-              (rec `(** ,(cadr sre) ,(cadr sre) ,@(cddr sre))))
-             ((>=)
-diff -ur a/irregex-utils.scm b/irregex-utils.scm
---- a/irregex-utils.scm	2016-09-11 19:03:00.000000000 -0400
-+++ b/irregex-utils.scm	2017-01-01 22:25:25.000000000 -0500
-@@ -89,7 +89,7 @@
-         (case (car x)
-           ((: seq)
-            (cond
--            ((and (pair? (cddr x)) (pair? (cddr x)) (not (eq? x obj)))
-+            ((and (pair? (cdr x)) (pair? (cddr x)) (not (eq? x obj)))
-              (display "(?:" out) (for-each lp (cdr x)) (display ")" out))
-             (else (for-each lp (cdr x)))))
-           ((submatch)
-diff -ur "a/manual-html/Unit irregex.html" "b/manual-html/Unit irregex.html"
---- "a/manual-html/Unit irregex.html"	2016-09-11 19:10:47.000000000 -0400
-+++ "b/manual-html/Unit irregex.html"	2017-01-01 22:26:05.000000000 -0500
-@@ -353,6 +353,6 @@
- <dd class="defsig"><p>Returns an optimized SRE matching any of the literal strings in the list, like Emacs' <tt>regexp-opt</tt>.  Note this optimization doesn't help when irregex is able to build a DFA.</p></dd>
- </dl>
- <h5 id="sec:sre-.3estring"><a href="#sec:sre-.3estring">sre-&gt;string</a></h5><dl class="defsig"><dt class="defsig" id="def:sre-.3estring"><span class="sig"><tt>(sre-&gt;string &lt;sre&gt;)</tt></span> <span class="type">procedure</span></dt>
--<dd class="defsig"><p>Convert an SRE to a POSIX-style regular expression string, if possible.</p></dd>
-+<dd class="defsig"><p>Convert an SRE to a PCRE-style regular expression string, if possible.</p></dd>
- </dl>
--<hr /><p>Previous: <a href="Unit%20extras.html">Unit extras</a></p><p>Next: <a href="Unit%20srfi-1.html">Unit srfi-1</a></p></div></div></body>
-\ No newline at end of file
-+<hr /><p>Previous: <a href="Unit%20extras.html">Unit extras</a></p><p>Next: <a href="Unit%20srfi-1.html">Unit srfi-1</a></p></div></div></body>
diff --git a/gnu/packages/patches/chicken-CVE-2017-6949.patch b/gnu/packages/patches/chicken-CVE-2017-6949.patch
new file mode 100644
index 0000000000..00552eec76
--- /dev/null
+++ b/gnu/packages/patches/chicken-CVE-2017-6949.patch
@@ -0,0 +1,132 @@
+From: LemonBoy <thatlemon@gmail.com>
+Date: Fri, 10 Mar 2017 16:29:47 +0100
+Subject: [PATCH] Add bound checking to all srfi-4 vector allocations.
+
+Do what C_allocate_vector already does and prevent the creation of a
+vector that's too big or too small.
+We should be very careful to avoid the latter case because the
+allocation size is directly fed into `malloc' as 'x + sizeof(C_header)'
+thus making possible to successfully allocate a vector smaller than the
+C_header structure and get C_block_header_init to write over
+uninitialized memory.
+
+To reduce code duplication, type checking is moved from each of the
+make-*vector procedures to the common "alloc" helper procedure.
+
+Signed-off-by: Peter Bex <peter@more-magic.net>
+Signed-off-by: Kooda <kooda@upyum.com>
+---
+ srfi-4.scm | 34 +++++++++++++++-------------------
+ 1 file changed, 15 insertions(+), 19 deletions(-)
+
+diff --git a/srfi-4.scm b/srfi-4.scm
+index 7f5412b..69f58ba 100644
+--- a/srfi-4.scm
++++ b/srfi-4.scm
+@@ -255,24 +255,28 @@ EOF
+ 
+ ;;; Basic constructors:
+ 
+-(let* ([ext-alloc
+-	(foreign-lambda* scheme-object ([int bytes])
+-	  "C_word *buf = (C_word *)C_malloc(bytes + sizeof(C_header));"
++(let* ((ext-alloc
++	(foreign-lambda* scheme-object ((size_t bytes))
++	  "C_word *buf;"
++	  "if (bytes > C_HEADER_SIZE_MASK) C_return(C_SCHEME_FALSE);"
++	  "buf = (C_word *)C_malloc(bytes + sizeof(C_header));"
+ 	  "if(buf == NULL) C_return(C_SCHEME_FALSE);"
+ 	  "C_block_header_init(buf, C_make_header(C_BYTEVECTOR_TYPE, bytes));"
+-	  "C_return(buf);") ]
+-       [ext-free
+-	(foreign-lambda* void ([scheme-object bv])
+-	  "C_free((void *)C_block_item(bv, 1));") ]
+-       [alloc
++	  "C_return(buf);") )
++       (ext-free
++	(foreign-lambda* void ((scheme-object bv))
++	  "C_free((void *)C_block_item(bv, 1));") )
++       (alloc
+ 	(lambda (loc len ext?)
++	  (##sys#check-exact len loc)
++	  (when (fx< len 0) (##sys#error loc "size is negative" len))
+ 	  (if ext?
+-	      (let ([bv (ext-alloc len)])
++	      (let ((bv (ext-alloc len)))
+ 		(or bv
+ 		    (##sys#error loc "not enough memory - cannot allocate external number vector" len)) )
+-	      (let ([bv (##sys#allocate-vector len #t #f #t)]) ; this could be made better...
++	      (let ((bv (##sys#allocate-vector len #t #f #t))) ; this could be made better...
+ 		(##core#inline "C_string_to_bytevector" bv)
+-		bv) ) ) ] )
++		bv) ) ) ) )
+ 
+   (set! release-number-vector
+     (lambda (v)
+@@ -282,7 +286,6 @@ EOF
+ 
+   (set! make-u8vector
+     (lambda (len #!optional (init #f)  (ext? #f) (fin? #t))
+-      (##sys#check-exact len 'make-u8vector)
+       (let ((v (##sys#make-structure 'u8vector (alloc 'make-u8vector len ext?))))
+ 	(when (and ext? fin?) (set-finalizer! v ext-free))
+ 	(if (not init)
+@@ -295,7 +298,6 @@ EOF
+ 
+   (set! make-s8vector
+     (lambda (len #!optional (init #f)  (ext? #f) (fin? #t))
+-      (##sys#check-exact len 'make-s8vector)
+       (let ((v (##sys#make-structure 's8vector (alloc 'make-s8vector len ext?))))
+ 	(when (and ext? fin?) (set-finalizer! v ext-free))
+ 	(if (not init)
+@@ -308,7 +310,6 @@ EOF
+ 
+   (set! make-u16vector
+     (lambda (len #!optional (init #f)  (ext? #f) (fin? #t))
+-      (##sys#check-exact len 'make-u16vector)
+       (let ((v (##sys#make-structure 'u16vector (alloc 'make-u16vector (##core#inline "C_fixnum_shift_left" len 1) ext?))))
+ 	(when (and ext? fin?) (set-finalizer! v ext-free))
+ 	(if (not init)
+@@ -321,7 +322,6 @@ EOF
+ 
+   (set! make-s16vector
+     (lambda (len #!optional (init #f)  (ext? #f) (fin? #t))
+-      (##sys#check-exact len 'make-s16vector)
+       (let ((v (##sys#make-structure 's16vector (alloc 'make-s16vector (##core#inline "C_fixnum_shift_left" len 1) ext?))))
+ 	(when (and ext? fin?) (set-finalizer! v ext-free))
+ 	(if (not init)
+@@ -334,7 +334,6 @@ EOF
+ 
+   (set! make-u32vector
+     (lambda (len #!optional (init #f)  (ext? #f) (fin? #t))
+-      (##sys#check-exact len 'make-u32vector)
+       (let ((v (##sys#make-structure 'u32vector (alloc 'make-u32vector (##core#inline "C_fixnum_shift_left" len 2) ext?))))
+ 	(when (and ext? fin?) (set-finalizer! v ext-free))
+ 	(if (not init)
+@@ -347,7 +346,6 @@ EOF
+ 
+   (set! make-s32vector
+     (lambda (len #!optional (init #f)  (ext? #f) (fin? #t))
+-      (##sys#check-exact len 'make-s32vector)
+       (let ((v (##sys#make-structure 's32vector (alloc 'make-s32vector (##core#inline "C_fixnum_shift_left" len 2) ext?))))
+ 	(when (and ext? fin?) (set-finalizer! v ext-free))
+ 	(if (not init)
+@@ -360,7 +358,6 @@ EOF
+ 
+   (set! make-f32vector
+     (lambda (len #!optional (init #f)  (ext? #f) (fin? #t))
+-      (##sys#check-exact len 'make-f32vector)
+       (let ((v (##sys#make-structure 'f32vector (alloc 'make-f32vector (##core#inline "C_fixnum_shift_left" len 2) ext?))))
+ 	(when (and ext? fin?) (set-finalizer! v ext-free))
+ 	(if (not init)
+@@ -375,7 +372,6 @@ EOF
+ 
+   (set! make-f64vector
+     (lambda (len #!optional (init #f)  (ext? #f) (fin? #t))
+-      (##sys#check-exact len 'make-f64vector)
+       (let ((v (##sys#make-structure
+ 		'f64vector
+ 		(alloc 'make-f64vector (##core#inline "C_fixnum_shift_left" len 3) ext?))))
+--
+2.1.4
+
diff --git a/gnu/packages/scheme.scm b/gnu/packages/scheme.scm
index e1dba9bed7..fec872f5f9 100644
--- a/gnu/packages/scheme.scm
+++ b/gnu/packages/scheme.scm
@@ -325,18 +325,16 @@ (define-public hop
 (define-public chicken
   (package
     (name "chicken")
-    (version "4.11.1")
+    (version "4.12.0")
     (source (origin
               (method url-fetch)
-              (uri (string-append "http://code.call-cc.org/releases/"
+              (uri (string-append "https://code.call-cc.org/releases/"
                                   version "/chicken-" version ".tar.gz"))
-              (uri (string-append "http://code.call-cc.org/dev-snapshots/"
-                                  "2016/09/12/chicken-" version ".tar.gz"))
               (sha256
                (base32
-                "1rwymbbmnwdyhdzilv9w75an989xw9kjf3x52iqdng3nphpflcga"))
+                "12b9gaa9lqh39lj1v4wm48f6z8ww3jdkvc5bh9gqqvn6kd2wwnk0"))
               (patches
-               (search-patches "chicken-CVE-2016-6830+CVE-2016-6831.patch"))))
+               (search-patches "chicken-CVE-2017-6949.patch"))))
     (build-system gnu-build-system)
     (arguments
      `(#:modules ((guix build gnu-build-system)
@@ -359,12 +357,6 @@ (define-public chicken
 
        ;; Parallel builds are not supported, as noted in README.
        #:parallel-build? #f))
-    ;; One of the tests ("testing direct invocation can detect calls of too
-    ;; many arguments...") times out when building with a more recent GCC.
-    ;; The problem was reported here:
-    ;; https://lists.gnu.org/archive/html/chicken-hackers/2015-04/msg00059.html
-    (native-inputs
-     `(("gcc" ,gcc-4.8)))
     (home-page "http://www.call-cc.org/")
     (synopsis "R5RS Scheme implementation that compiles native code via C")
     (description