diff --git a/tests/functional/test-infra.sh b/tests/functional/test-infra.sh
index 1dab069fb..d02a11b46 100755
--- a/tests/functional/test-infra.sh
+++ b/tests/functional/test-infra.sh
@@ -111,7 +111,7 @@ unset res
 
 # `grepQuiet` does not allow newlines in its arguments, because grep quietly
 # treats them as multiple queries.
-( echo foo; echo bar; ) | expectStderr -101 grepQuiet $'foo\nbar' \
+{ echo foo; echo bar; } | expectStderr -101 grepQuiet $'foo\nbar' \
   | grepQuiet -E 'test-infra\.sh:[0-9]+: in call to grepQuiet: newline not allowed in arguments; grep would try each line individually as if connected by an OR operator'
 
 # We took the blue pill and woke up in a world where `grep` is moderately safe.