diff --git a/pkgs/development/compilers/rustc/0.12.nix b/pkgs/development/compilers/rustc/0.12.nix
index 43df15505c0d..7b7dc3198b47 100644
--- a/pkgs/development/compilers/rustc/0.12.nix
+++ b/pkgs/development/compilers/rustc/0.12.nix
@@ -1,5 +1,7 @@
 {stdenv, fetchurl, which, file, perl, curl, python27, makeWrapper}:
 
+assert !stdenv.isFreeBSD;
+
 /* Rust's build process has a few quirks :
 
 - It requires some patched in llvm that haven't landed upstream, so it
diff --git a/pkgs/development/compilers/rustc/head.nix b/pkgs/development/compilers/rustc/head.nix
index f71236c50051..713a5b779a45 100644
--- a/pkgs/development/compilers/rustc/head.nix
+++ b/pkgs/development/compilers/rustc/head.nix
@@ -2,6 +2,8 @@
 , tzdata, git, valgrind, procps, coreutils
 }:
 
+assert !stdenv.isFreeBSD;
+
 /* Rust's build process has a few quirks :
 
 - It requires some patched in llvm that haven't landed upstream, so it