diff --git a/tests/functional/derivation-json.sh b/tests/functional/derivation-json.sh
index 59c77e6c5..06f934cfe 100755
--- a/tests/functional/derivation-json.sh
+++ b/tests/functional/derivation-json.sh
@@ -4,11 +4,11 @@ source common.sh
 
 drvPath=$(nix-instantiate simple.nix)
 
-nix derivation show $drvPath | jq .[] > $TEST_HOME/simple.json
+nix derivation show "$drvPath" | jq .[] > "$TEST_HOME"/simple.json
 
-drvPath2=$(nix derivation add < $TEST_HOME/simple.json)
+drvPath2=$(nix derivation add < "$TEST_HOME"/simple.json)
 
 [[ "$drvPath" = "$drvPath2" ]]
 
 # Input addressed derivations cannot be renamed.
-jq '.name = "foo"' < $TEST_HOME/simple.json | expectStderr 1 nix derivation add | grepQuiet "has incorrect output"
+jq '.name = "foo"' < "$TEST_HOME"/simple.json | expectStderr 1 nix derivation add | grepQuiet "has incorrect output"