diff --git a/pkgs/development/compilers/swift/libdispatch/default.nix b/pkgs/development/compilers/swift/libdispatch/default.nix
index 3fe536c1889f5..4a0616ded5ac5 100644
--- a/pkgs/development/compilers/swift/libdispatch/default.nix
+++ b/pkgs/development/compilers/swift/libdispatch/default.nix
@@ -6,7 +6,9 @@
 , useSwift ? true, swift
 }:
 
-stdenv.mkDerivation {
+let
+  sources = callPackage ../sources.nix { };
+in stdenv.mkDerivation {
   pname = "swift-corelibs-libdispatch";
 
   inherit (sources) version;