diff --git a/garlic/stages/isolate/default.nix b/garlic/stages/isolate/default.nix
index b8c0722..9ca73e0 100644
--- a/garlic/stages/isolate/default.nix
+++ b/garlic/stages/isolate/default.nix
@@ -9,10 +9,16 @@
   nextStage
 , nixPrefix
 , clusterName ? "mn4"
+, extraMounts ? []
 }:
 
 with garlicTools;
+with builtins;
 
+let
+  slashM = map (line: "-m ${line}") extraMounts;
+  extraMountOptions = concatStringsSep "\n" slashM;
+in
 stdenv.mkDerivation {
   name = "isolate";
   preferLocalBuild = true;
@@ -20,7 +26,7 @@ stdenv.mkDerivation {
   src = ./.;
   dontPatchShebangs = true;
   programPath = "/bin/stage1";
-  inherit nixPrefix clusterName nixtools busybox;
+  inherit nixPrefix clusterName nixtools busybox extraMountOptions;
   inherit nextStage;
   program = stageProgram nextStage;
   desc = "#  $out\n" + (if builtins.hasAttr "desc" nextStage then nextStage.desc else "");
diff --git a/garlic/stages/isolate/stage1 b/garlic/stages/isolate/stage1
index 4b97bd2..6a624cd 100644
--- a/garlic/stages/isolate/stage1
+++ b/garlic/stages/isolate/stage1
@@ -19,6 +19,7 @@ env=(
   $(env | grep ^PMI || true)
   $(env | grep ^GARLIC || true)
   $(env | grep ^USER || true)
+  $(env | grep ^TMPDIR || true)
   HOME="/homeless-shelter"
 )
 
@@ -39,6 +40,7 @@ mounts=(
 	-m /gpfs/projects/bsc15
 	-m /gpfs/scratch/bsc15
 	-m /bin:@nixPrefix@@busybox@/bin
+  @extraMountOptions@
 )
 
 join_flags="${mounts[@]}"
diff --git a/garlic/stdexp.nix b/garlic/stdexp.nix
index 880a504..cb208f7 100644
--- a/garlic/stdexp.nix
+++ b/garlic/stdexp.nix
@@ -75,11 +75,17 @@ rec {
       }
     );
 
-    isolate = {nextStage, conf, ...}: stages.isolate {
-      clusterName = machineConf.name;
-      inherit (conf) nixPrefix;
-      inherit nextStage;
-    };
+    isolate = {nextStage, conf, ...}: stages.isolate (
+      (
+        if (conf ? extraMounts) then { inherit (conf) extraMounts; }
+        else {}
+      ) //
+      {
+        clusterName = machineConf.name;
+        inherit (conf) nixPrefix;
+        inherit nextStage;
+      }
+    );
   };
 
   stdPipelineOverride = {overrides ? {}}: