diff --git a/internal/lsp/regtest/cgo_test.go b/internal/lsp/regtest/cgo_test.go
deleted file mode 100644
index 2abd3dd398..0000000000
--- a/internal/lsp/regtest/cgo_test.go
+++ /dev/null
@@ -1,58 +0,0 @@
-//+build go1.15
-
-package regtest
-
-import (
-	"testing"
-
-	"golang.org/x/tools/internal/lsp/protocol"
-	"golang.org/x/tools/internal/lsp/source"
-	"golang.org/x/tools/internal/testenv"
-)
-
-func TestRegenerateCgo(t *testing.T) {
-	t.Skip("This test fails in some environments: see golang.org/issues/39135")
-	testenv.NeedsTool(t, "cgo")
-
-	const workspace = `
--- go.mod --
-module example.com
--- cgo.go --
-package x
-
-/*
-int fortythree() { return 42; }
-*/
-import "C"
-
-func Foo() {
-	print(C.fortytwo())
-}
-`
-	runner.Run(t, workspace, func(t *testing.T, env *Env) {
-		// Open the file. We should have a nonexistant symbol.
-		env.OpenFile("cgo.go")
-		env.Await(env.DiagnosticAtRegexp("cgo.go", `C\.(fortytwo)`)) // could not determine kind of name for C.fortytwo
-
-		// Fix the C function name. We haven't regenerated cgo, so nothing should be fixed.
-		env.RegexpReplace("cgo.go", `int fortythree`, "int fortytwo")
-		env.SaveBuffer("cgo.go")
-		env.Await(env.DiagnosticAtRegexp("cgo.go", `C\.(fortytwo)`))
-
-		// Regenerate cgo, fixing the diagnostic.
-		lenses := env.CodeLens("cgo.go")
-		var lens protocol.CodeLens
-		for _, l := range lenses {
-			if l.Command.Command == source.CommandRegenerateCgo {
-				lens = l
-			}
-		}
-		if _, err := env.Editor.Server.ExecuteCommand(env.Ctx, &protocol.ExecuteCommandParams{
-			Command:   lens.Command.Command,
-			Arguments: lens.Command.Arguments,
-		}); err != nil {
-			t.Fatal(err)
-		}
-		env.Await(EmptyDiagnostics("cgo.go"))
-	})
-}
diff --git a/internal/lsp/regtest/codelens_test.go b/internal/lsp/regtest/codelens_test.go
index 41bc53d4ef..42c5f74216 100644
--- a/internal/lsp/regtest/codelens_test.go
+++ b/internal/lsp/regtest/codelens_test.go
@@ -10,6 +10,7 @@ import (
 	"golang.org/x/tools/internal/lsp/fake"
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/testenv"
 )
 
 func TestDisablingCodeLens(t *testing.T) {
@@ -118,3 +119,50 @@ func main() {
 		}
 	}, WithProxy(proxyWithLatest))
 }
+
+func TestRegenerateCgo(t *testing.T) {
+	testenv.NeedsTool(t, "cgo")
+	testenv.NeedsGo1Point(t, 15)
+
+	const workspace = `
+-- go.mod --
+module example.com
+-- cgo.go --
+package x
+
+/*
+int fortythree() { return 42; }
+*/
+import "C"
+
+func Foo() {
+	print(C.fortytwo())
+}
+`
+	runner.Run(t, workspace, func(t *testing.T, env *Env) {
+		// Open the file. We should have a nonexistant symbol.
+		env.OpenFile("cgo.go")
+		env.Await(env.DiagnosticAtRegexp("cgo.go", `C\.(fortytwo)`)) // could not determine kind of name for C.fortytwo
+
+		// Fix the C function name. We haven't regenerated cgo, so nothing should be fixed.
+		env.RegexpReplace("cgo.go", `int fortythree`, "int fortytwo")
+		env.SaveBuffer("cgo.go")
+		env.Await(env.DiagnosticAtRegexp("cgo.go", `C\.(fortytwo)`))
+
+		// Regenerate cgo, fixing the diagnostic.
+		lenses := env.CodeLens("cgo.go")
+		var lens protocol.CodeLens
+		for _, l := range lenses {
+			if l.Command.Command == source.CommandRegenerateCgo {
+				lens = l
+			}
+		}
+		if _, err := env.Editor.Server.ExecuteCommand(env.Ctx, &protocol.ExecuteCommandParams{
+			Command:   lens.Command.Command,
+			Arguments: lens.Command.Arguments,
+		}); err != nil {
+			t.Fatal(err)
+		}
+		env.Await(EmptyDiagnostics("cgo.go"))
+	})
+}