diff --git a/src/cmd/go/testdata/script/mod_sumdb_proxy.txt b/src/cmd/go/testdata/script/mod_sumdb_proxy.txt
index 52f6a10fba..6fbf7aeb8a 100644
--- a/src/cmd/go/testdata/script/mod_sumdb_proxy.txt
+++ b/src/cmd/go/testdata/script/mod_sumdb_proxy.txt
@@ -17,11 +17,14 @@ rm $GOPATH/pkg/mod/download/cache/sumdb
 rm go.sum
 
 # direct access fails (because localhost.localdev does not exist)
+# The text of the error message is hard to predict because some DNS servers
+# will resolve unknown domains like localhost.localdev to a real IP
+# to serve ads.
 cp go.mod.orig go.mod
 env GOSUMDB=$sumdb
 env GOPROXY=direct
 ! go get -d rsc.io/fortune@v1.0.0
-stderr 'verifying.*lookup.*localhost.localdev'
+stderr 'verifying.*localhost.localdev'
 rm $GOPATH/pkg/mod/download/cache/sumdb
 rm go.sum
 
@@ -30,7 +33,7 @@ cp go.mod.orig go.mod
 env GOSUMDB=$sumdb
 env GOPROXY=$proxy/sumdb-404
 ! go get -d rsc.io/fortune@v1.0.0
-stderr 'verifying.*lookup.*localhost.localdev'
+stderr 'verifying.*localhost.localdev'
 rm $GOPATH/pkg/mod/download/cache/sumdb
 rm go.sum