diff --git a/site_scons/gem5_scons/defaults.py b/site_scons/gem5_scons/defaults.py
index 2a4e0204c8..a07b7ffa4b 100644
--- a/site_scons/gem5_scons/defaults.py
+++ b/site_scons/gem5_scons/defaults.py
@@ -77,6 +77,7 @@ def EnvDefaults(env):
         "INCLUDE_SERVER_",  # distcc pump server settings
         "M5",  # M5 configuration (e.g., path to kernels)
         "NIX_",  # wrapped binaries if using nix package manager
+        "TMPDIR",  # default temporary directory
     ]
 
     for key, val in sorted(os.environ.items()):