diff --git a/pkgs/development/compilers/gcc/5/default.nix b/pkgs/development/compilers/gcc/5/default.nix
index 536433ff3c6..57b68d1a11f 100644
--- a/pkgs/development/compilers/gcc/5/default.nix
+++ b/pkgs/development/compilers/gcc/5/default.nix
@@ -491,7 +491,7 @@ stdenv.mkDerivation ({
 
     # On GNU/Hurd glibc refers to Mach & Hurd
     # headers.
-    ++ optionals (libcCross != null && libcCross ? "propagatedBuildInputs")
+    ++ optionals (libcCross != null && libcCross ? propagatedBuildInputs)
                  libcCross.propagatedBuildInputs);
 
   LIBRARY_PATH = makeLibraryPath ([]