diff --git a/pkgs/development/compilers/gambit/unstable.nix b/pkgs/development/compilers/gambit/unstable.nix
index 7c4434acdc3..3ac4f536319 100644
--- a/pkgs/development/compilers/gambit/unstable.nix
+++ b/pkgs/development/compilers/gambit/unstable.nix
@@ -1,13 +1,13 @@
 { callPackage, fetchFromGitHub, gambit-support }:
 
 callPackage ./build.nix {
-  version = "unstable-2020-02-24";
-  git-version = "4.9.3-979-gc69e9f70";
+  version = "unstable-2020-05-15";
+  git-version = "4.9.3-1109-g3c4d40de";
   src = fetchFromGitHub {
     owner = "feeley";
     repo = "gambit";
-    rev = "c69e9f70dfdc6545353b135a5d5e2f9234f1e1cc";
-    sha256 = "1f69n7yzzdv3wpnjlrbck38xpa8115vbady43mc544l39ckklr0k";
+    rev = "3c4d40de908ae03ca0e3d854edc2234ef401b36c";
+    sha256 = "1c9a6rys2kiiqb79gvw29nv3dwwk6hmi1q4jk1whcx7mds7q5dvr";
   };
   gambit-params = gambit-support.unstable-params;
 }