diff --git a/pkgs/development/compilers/gambit/default.nix b/pkgs/development/compilers/gambit/default.nix
index 0996d0c3078a..93f1d9184b4d 100644
--- a/pkgs/development/compilers/gambit/default.nix
+++ b/pkgs/development/compilers/gambit/default.nix
@@ -1,13 +1,11 @@
-{ callPackage, fetchgit }:
+{ callPackage, fetchurl }:
 
 callPackage ./build.nix {
   version = "4.8.9";
-  # TODO: for next version, prefer the unpatched tarball for the stable/default gambit.
-  git-version = "4.8.9-8-g793679bd";
+  git-version = "4.8.9";
 
-  SRC = fetchgit {
-    url = "https://github.com/feeley/gambit.git";
-    rev = "dd54a71dfc0bd09813592f1645d755867a02195d";
-    sha256 = "120kg73k39gshrwas8a3xcrxgnq1c7ww92wgy4d3mmrwy3j9nzzc";
+  SRC = fetchurl {
+    url = "http://www.iro.umontreal.ca/~gambit/download/gambit/v4.8/source/gambit-v4_8_9-devel.tgz";
+    sha256 = "1gwzz1ag9hlv266nvfq1bhwzrps3f2yghhffasjjqy8i8xwnry5p";
   };
 }
diff --git a/pkgs/development/compilers/gambit/unstable.nix b/pkgs/development/compilers/gambit/unstable.nix
index f98fd5ca935a..545bece12c48 100644
--- a/pkgs/development/compilers/gambit/unstable.nix
+++ b/pkgs/development/compilers/gambit/unstable.nix
@@ -1,11 +1,11 @@
 { callPackage, fetchgit }:
 
 callPackage ./build.nix {
-  version = "unstable-2018-03-26";
-  git-version = "4.8.9-8-g793679bd";
+  version = "unstable-2018-05-30";
+  git-version = "4.8.9-54-gffe8841b";
   SRC = fetchgit {
     url = "https://github.com/feeley/gambit.git";
-    rev = "793679bd57eb6275cb06e6570b05f4a78df61bf9";
-    sha256 = "0bippvmrc8vcaa6ka3mhzfgkagb6a1616g7nxk0i0wapxai5cngj";
+    rev = "ffe8841b56330eb86fd794b16dc7f83914ecc7c5";
+    sha256 = "1xzkwa2f6zazybbgd5zynhr36krayhr29vsbras5ld63hkrxrp7q";
   };
 }
diff --git a/pkgs/development/compilers/gerbil/unstable.nix b/pkgs/development/compilers/gerbil/unstable.nix
index ec36f42d86e6..25c6b75fa03e 100644
--- a/pkgs/development/compilers/gerbil/unstable.nix
+++ b/pkgs/development/compilers/gerbil/unstable.nix
@@ -1,12 +1,12 @@
 { callPackage, fetchgit, gambit-unstable }:
 
 callPackage ./build.nix {
-  version = "unstable-2018-04-03";
-  git-version = "0.13-DEV-357-ge61318dc";
+  version = "unstable-2018-05-12";
+  git-version = "0.13-DEV-437-gaefdb47f";
   GAMBIT = gambit-unstable;
   SRC = fetchgit {
     url = "https://github.com/vyzo/gerbil.git";
-    rev = "e61318dcaa3a9c843e2cf259e67851f240e4beda";
-    sha256 = "1xd7yxiramifdxgp6b3s24z6nkkmy5h4a6pkchvy4w358qv1vqin";
+    rev = "aefdb47f3d1ceaa735fd5c3dcaac2aeb0d4d2436";
+    sha256 = "0xhsilm5kix5lsmykv273npp1gk6dgx9axh266mimwh7j0nxf7ms";
   };
 }