diff --git a/nix/default.nix b/nix/default.nix
index c3d35503553f640dfc80aae2a6dc5984c517c536..c212c758009c9a9c2ae0e6bd33af0148797f48b8 100644
--- a/nix/default.nix
+++ b/nix/default.nix
@@ -44,17 +44,17 @@ rec {
         '';
         setupHook = pkgs.writeText "setupHook.sh" ''
           addFramaCPath () {
-            if test -d "''$1/lib/frama-c/plugins"; then
-              export FRAMAC_PLUGIN="''${FRAMAC_PLUGIN:-}''${FRAMAC_PLUGIN:+:}''$1/lib/frama-c/plugins"
-              export OCAMLPATH="''${OCAMLPATH:-}''${OCAMLPATH:+:}''$1/lib/frama-c/plugins"
+            if test -d "$1/lib/frama-c/plugins"; then
+              export FRAMAC_PLUGIN="''${FRAMAC_PLUGIN:-}''${FRAMAC_PLUGIN:+:}$1/lib/frama-c/plugins"
+              export OCAMLPATH="''${OCAMLPATH:-}''${OCAMLPATH:+:}$1/lib/frama-c/plugins"
             fi
 
-            if test -d "''$1/lib/frama-c"; then
-              export OCAMLPATH="''${OCAMLPATH:-}''${OCAMLPATH:+:}''$1/lib/frama-c"
+            if test -d "$1/lib/frama-c"; then
+              export OCAMLPATH="''${OCAMLPATH:-}''${OCAMLPATH:+:}$1/lib/frama-c"
             fi
 
-            if test -d "''$1/share/frama-c/"; then
-              export FRAMAC_EXTRA_SHARE="''${FRAMAC_EXTRA_SHARE:-}''${FRAMAC_EXTRA_SHARE:+:}''$1/share/frama-c"
+            if test -d "$1/share/frama-c/"; then
+              export FRAMAC_EXTRA_SHARE="''${FRAMAC_EXTRA_SHARE:-}''${FRAMAC_EXTRA_SHARE:+:}$1/share/frama-c"
             fi
 
           }