diff --git a/pkgs/servers/home-assistant/default.nix b/pkgs/servers/home-assistant/default.nix
index a57f0d32c4a6..dc6c17f4d514 100644
--- a/pkgs/servers/home-assistant/default.nix
+++ b/pkgs/servers/home-assistant/default.nix
@@ -535,7 +535,7 @@ in python.pkgs.buildPythonApplication rec {
   ];
 
   postPatch = ''
-    substituteInPlace tests/test_config.py --replace-fail '"/usr"' '"/build/media"'
+    substituteInPlace tests/test_config.py --replace-fail '"/usr"' "\"$NIX_BUILD_TOP/media\""
 
     substituteInPlace pyproject.toml --replace-fail "wheel~=0.43.0" wheel
 
@@ -665,7 +665,7 @@ in python.pkgs.buildPythonApplication rec {
     export HOME="$TEMPDIR"
 
     # the tests require the existance of a media dir
-    mkdir /build/media
+    mkdir "$NIX_BUILD_TOP"/media
 
     # put ping binary into PATH, e.g. for wake_on_lan tests
     export PATH=${inetutils}/bin:$PATH