diff --git a/pkgs/development/compilers/gcc-4.5/default.nix b/pkgs/development/compilers/gcc-4.5/default.nix
index 77e3cbfa3ed..19efa57af8e 100644
--- a/pkgs/development/compilers/gcc-4.5/default.nix
+++ b/pkgs/development/compilers/gcc-4.5/default.nix
@@ -180,7 +180,7 @@ stdenv.mkDerivation ({
       # On NixOS, use the right path to the dynamic linker instead of
       # `/lib/ld*.so'.
       let
-        libc = if cross != null then libcCross else stdenv.gcc.libc;
+        libc = if (cross != null && libcCross != null) then libcCross else stdenv.gcc.libc;
       in
         '' echo "fixing the \`GLIBC_DYNAMIC_LINKER' and \`UCLIBC_DYNAMIC_LINKER' macros..."
            for header in "gcc/config/"*-gnu.h "gcc/config/"*"/"*.h