diff --git a/pkgs/os-specific/linux/pam/default.nix b/pkgs/os-specific/linux/pam/default.nix
index d7d4f1a43d4..c18ea2b1f2b 100644
--- a/pkgs/os-specific/linux/pam/default.nix
+++ b/pkgs/os-specific/linux/pam/default.nix
@@ -11,7 +11,7 @@ stdenv.mkDerivation rec {
   buildNativeInputs = [ flex ];
   buildInputs = [ cracklib ]
     ++ stdenv.lib.optional
-      (stdenv.isArm && stdenv.system != "mips64el-linux")
+      (!stdenv.isArm && stdenv.system != "mips64el-linux")
       libxcrypt;
 
   crossAttrs = {