diff --git a/pkgs/development/compilers/gambit/default.nix b/pkgs/development/compilers/gambit/default.nix
index 36aa73f7274b..812b83389601 100644
--- a/pkgs/development/compilers/gambit/default.nix
+++ b/pkgs/development/compilers/gambit/default.nix
@@ -1,11 +1,11 @@
 { stdenv, callPackage, fetchurl }:
 
 callPackage ./build.nix {
-  version = "4.8.9";
+  version = "4.9.0";
 
   SRC = fetchurl {
-    url = "http://www.iro.umontreal.ca/~gambit/download/gambit/v4.8/source/gambit-v4_8_9-devel.tgz";
-    sha256 = "1gwzz1ag9hlv266nvfq1bhwzrps3f2yghhffasjjqy8i8xwnry5p";
+    url = "http://www.iro.umontreal.ca/~gambit/download/gambit/v4.9/source/gambit-v4_9_0-devel.tgz";
+    sha256 = "0wyfpjs244zrbrdil9rfkdgcawvms84z0r77qwhwadghma4dqgjf";
   };
   inherit stdenv;
 }
diff --git a/pkgs/development/compilers/gambit/unstable.nix b/pkgs/development/compilers/gambit/unstable.nix
index 41d0ee930bf0..067a409ac1c3 100644
--- a/pkgs/development/compilers/gambit/unstable.nix
+++ b/pkgs/development/compilers/gambit/unstable.nix
@@ -1,12 +1,12 @@
 { stdenv, callPackage, fetchgit }:
 
 callPackage ./build.nix {
-  version = "unstable-2018-08-06";
-# git-version = "4.8.9-77-g91a4ad2c";
+  version = "unstable-2018-09-03";
+# git-version = "4.9.0";
   SRC = fetchgit {
     url = "https://github.com/feeley/gambit.git";
-    rev = "91a4ad2c28375f067adedcaa61f9d66a4b536f4f";
-    sha256 = "0px1ipvhh0hz8n38h6jv4y1nn163j8llvcy4l7p3hkdns5czwy1p";
+    rev = "7cdc7e7b9194b2c088c0667efaf7686a4ffd0d8a";
+    sha256 = "06mmi8jkinihfirz4gjfw2lhxhskiqf3d47sihzx10r60asyqcxg";
   };
   inherit stdenv;
 }
diff --git a/pkgs/development/compilers/gerbil/default.nix b/pkgs/development/compilers/gerbil/default.nix
index 6fa9fcc3de88..e0f4ca4324f0 100644
--- a/pkgs/development/compilers/gerbil/default.nix
+++ b/pkgs/development/compilers/gerbil/default.nix
@@ -1,12 +1,12 @@
 { stdenv, callPackage, fetchurl, gambit }:
 
 callPackage ./build.nix {
-  version = "0.12-RELEASE";
-  git-version = "0.12";
+  version = "0.13";
+  git-version = "0.13";
   GAMBIT = gambit;
   SRC = fetchurl {
-    url = "https://github.com/vyzo/gerbil/archive/v0.12.tar.gz";
-    sha256 = "0nigr3mgrzai57q2jqac8f39zj8rcmic3277ynyzlgm8hhps71pq";
+    url = "https://github.com/vyzo/gerbil/archive/v0.13.tar.gz";
+    sha256 = "1qs0vdq2lgxlpw20s8jzw2adx1xk9wb3w2m4a8vp6bb8hagmfr5l";
   };
   inherit stdenv;
 }
diff --git a/pkgs/development/compilers/gerbil/unstable.nix b/pkgs/development/compilers/gerbil/unstable.nix
index 66ead04b5429..bd9c3994dd49 100644
--- a/pkgs/development/compilers/gerbil/unstable.nix
+++ b/pkgs/development/compilers/gerbil/unstable.nix
@@ -1,13 +1,13 @@
 { stdenv, callPackage, fetchgit, gambit-unstable }:
 
 callPackage ./build.nix {
-  version = "unstable-2018-08-11";
-  git-version = "0.13-DEV-542-g274e1a22";
+  version = "unstable-2018-09-06";
+  git-version = "0.14-DEV";
   GAMBIT = gambit-unstable;
   SRC = fetchgit {
     url = "https://github.com/vyzo/gerbil.git";
-    rev = "274e1a22b2d2b708d5582594274ab52ee9ba1686";
-    sha256 = "10j44ar4xfl8xmh276zg1ykd3r0vy7w2f2cg4p8slwnk9r251g2s";
+    rev = "184cb635c82517d5d75d7966dcdf1d25ad863dac";
+    sha256 = "1ljzbpc36i9zpzfwra5hpfbgzj1dyzzp50h5jf976n8qr9x4l7an";
   };
   inherit stdenv;
 }