diff --git a/pkgs/development/compilers/ghcjs/default.nix b/pkgs/development/compilers/ghcjs/default.nix
index 722c3eab10ae..808768f74b86 100644
--- a/pkgs/development/compilers/ghcjs/default.nix
+++ b/pkgs/development/compilers/ghcjs/default.nix
@@ -38,7 +38,16 @@
 , coreutils
 , libiconv
 
-, ghcjsBoot ? import ./ghcjs-boot.nix { inherit fetchgit runCommand; }
+, ghcjsBootSrc ? fetchgit {
+    url = git://github.com/ghcjs/ghcjs-boot.git;
+    rev = "97dea5c4145bf80a1e7cffeb1ecd4d0ecacd5a2f";
+    sha256 = "1cgjzm595l2dx6fibzbkyv23bp1857qia0hb9d8aghf006al558j";
+    fetchSubmodules = true;
+  }
+, ghcjsBoot ? import ./ghcjs-boot.nix {
+    inherit runCommand;
+    src = ghcjsBootSrc;
+  }
 , shims ? import ./shims.nix { inherit fetchFromGitHub; }
 }:
 let
diff --git a/pkgs/development/compilers/ghcjs/ghcjs-boot.nix b/pkgs/development/compilers/ghcjs/ghcjs-boot.nix
index add39a35242b..c00e13a92404 100644
--- a/pkgs/development/compilers/ghcjs/ghcjs-boot.nix
+++ b/pkgs/development/compilers/ghcjs/ghcjs-boot.nix
@@ -1,14 +1,4 @@
-{ runCommand, fetchgit }:
-
-let
-  src = fetchgit {
-    url = git://github.com/ghcjs/ghcjs-boot.git;
-    rev = "97dea5c4145bf80a1e7cffeb1ecd4d0ecacd5a2f";
-    sha256 = "1cgjzm595l2dx6fibzbkyv23bp1857qia0hb9d8aghf006al558j";
-    fetchSubmodules = true;
-  };
-
-in
+{ runCommand, src }:
 
 # we remove the patches so ghcjs-boot doesn't try to apply them again.
 runCommand "${src.name}-patched" {} ''