diff --git a/pkgs/build-support/release/source-tarball.nix b/pkgs/build-support/release/source-tarball.nix
index 94566e4c460..16ac0033d93 100644
--- a/pkgs/build-support/release/source-tarball.nix
+++ b/pkgs/build-support/release/source-tarball.nix
@@ -6,16 +6,15 @@
 , buildInputs ? []
 , name ? "source-tarball"
 , version ? "0"
+, versionSuffix ? 
+    if officialRelease
+    then ""
+    else if src ? rev then "pre${toString src.rev}" else ""
 , src, stdenv, autoconf, automake, libtool
 , ... } @ args:
 
 let
 
-  versionSuffix =
-    if officialRelease
-    then ""
-    else if src ? rev then "pre${toString src.rev}" else "";
-
   # By default, provide all the GNU Build System as input.
   bootstrapBuildInputs =
     if (args ? bootstrapBuildInputs)