diff --git a/tests/functional/logging.sh b/tests/functional/logging.sh
index bbc1bac96..ddb1913ad 100755
--- a/tests/functional/logging.sh
+++ b/tests/functional/logging.sh
@@ -29,5 +29,7 @@ test -d "$outp"
 
 nix log "$outp"
 
-# Build works despite ill-formed structured build log entries.
-expectStderr 0 nix build -f ./logging/unusual-logging.nix --no-link | grepQuiet 'warning: Unable to handle a JSON message from the derivation builder:'
+if isDaemonNewer "2.26"; then
+    # Build works despite ill-formed structured build log entries.
+    expectStderr 0 nix build -f ./logging/unusual-logging.nix --no-link | grepQuiet 'warning: Unable to handle a JSON message from the derivation builder:'
+fi