diff --git a/go/packages/packagestest/modules.go b/go/packages/packagestest/modules.go
index 2e06612c..6d46d9ba 100644
--- a/go/packages/packagestest/modules.go
+++ b/go/packages/packagestest/modules.go
@@ -116,7 +116,9 @@ func (modules) Finalize(exported *Exported) error {
 	exported.Config.Env = append(exported.Config.Env,
 		"GO111MODULE=on",
 		"GOPATH="+filepath.Join(exported.temp, "modcache"),
-		"GOPROXY="+proxyDirToURL(proxyDir))
+		"GOPROXY="+proxyDirToURL(proxyDir),
+		"GOSUMDB=off",
+	)
 
 	// Run go mod download to recreate the mod cache dir with all the extra
 	// stuff in cache. All the files created by Export should be recreated.
diff --git a/internal/imports/fix.go b/internal/imports/fix.go
index 3af3a142..7a465b7d 100644
--- a/internal/imports/fix.go
+++ b/internal/imports/fix.go
@@ -506,8 +506,8 @@ type ProcessEnv struct {
 
 	// If non-empty, these will be used instead of the
 	// process-wide values.
-	GOPATH, GOROOT, GO111MODULE, GOPROXY, GOFLAGS string
-	WorkingDir                                    string
+	GOPATH, GOROOT, GO111MODULE, GOPROXY, GOFLAGS, GOSUMDB string
+	WorkingDir                                             string
 
 	// If true, use go/packages regardless of the environment.
 	ForceGoPackages bool
@@ -527,6 +527,7 @@ func (e *ProcessEnv) env() []string {
 	add("GO111MODULE", e.GO111MODULE)
 	add("GOPROXY", e.GOPROXY)
 	add("GOFLAGS", e.GOFLAGS)
+	add("GOSUMDB", e.GOSUMDB)
 	if e.WorkingDir != "" {
 		add("PWD", e.WorkingDir)
 	}
diff --git a/internal/imports/fix_test.go b/internal/imports/fix_test.go
index 4f106969..3a8445a2 100644
--- a/internal/imports/fix_test.go
+++ b/internal/imports/fix_test.go
@@ -1572,6 +1572,7 @@ func (c testConfig) test(t *testing.T, fn func(*goimportTest)) {
 					GOROOT:          env["GOROOT"],
 					GOPATH:          env["GOPATH"],
 					GO111MODULE:     env["GO111MODULE"],
+					GOSUMDB:         env["GOSUMDB"],
 					WorkingDir:      exported.Config.Dir,
 					ForceGoPackages: forceGoPackages,
 					Debug:           *testDebug,
diff --git a/internal/imports/mod_test.go b/internal/imports/mod_test.go
index cda41470..590b1c89 100644
--- a/internal/imports/mod_test.go
+++ b/internal/imports/mod_test.go
@@ -520,6 +520,7 @@ func setup(t *testing.T, main, wd string) *modTest {
 		GOPATH:      filepath.Join(dir, "gopath"),
 		GO111MODULE: "on",
 		GOPROXY:     proxyDirToURL(proxyDir),
+		GOSUMDB:     "off",
 		WorkingDir:  filepath.Join(mainDir, wd),
 	}