diff --git a/tests/functional/nars.sh b/tests/functional/nars.sh
index 39d9389db..dd90345a6 100755
--- a/tests/functional/nars.sh
+++ b/tests/functional/nars.sh
@@ -134,7 +134,7 @@ rm -f "$TEST_ROOT/unicode-*"
 
 # Unpacking a NAR with a NUL character in a file name should fail.
 rm -rf "$TEST_ROOT/out"
-expectStderr 1 nix-store --restore "$TEST_ROOT/out" < nul.nar | grepQuiet "NAR contains invalid file name 'f"
+expectStderr 1 nix-store --restore "$TEST_ROOT/out" < nul-character.nar | grepQuiet "NAR contains invalid file name 'f"
 
 # Likewise for a '.' filename.
 rm -rf "$TEST_ROOT/out"
diff --git a/tests/functional/nul.nar b/tests/functional/nul-character.nar
similarity index 100%
rename from tests/functional/nul.nar
rename to tests/functional/nul-character.nar