diff --git a/go/expect/expect_test.go b/go/expect/expect_test.go
index bd25ef8..e9ae40f 100644
--- a/go/expect/expect_test.go
+++ b/go/expect/expect_test.go
@@ -43,7 +43,7 @@
 			},
 		},
 		{
-			filename:    "testdata/go.mod",
+			filename:    "testdata/go.fake.mod",
 			expectNotes: 2,
 			expectMarkers: map[string]string{
 				"αMarker": "αfake1α",
diff --git a/go/expect/testdata/go.fake.mod b/go/expect/testdata/go.fake.mod
new file mode 100644
index 0000000..ca84fce
--- /dev/null
+++ b/go/expect/testdata/go.fake.mod
@@ -0,0 +1,9 @@
+// This file is named go.fake.mod so it does not define a real module, which
+// would make the contents of this directory unavailable to the test when run
+// from outside the repository.
+
+module αfake1α //@mark(αMarker, "αfake1α")
+
+go 1.14
+
+require golang.org/modfile v0.0.0 //@mark(βMarker, "require golang.org/modfile v0.0.0")
diff --git a/go/expect/testdata/go.mod b/go/expect/testdata/go.mod
deleted file mode 100644
index d0323ea..0000000
--- a/go/expect/testdata/go.mod
+++ /dev/null
@@ -1,5 +0,0 @@
-module αfake1α //@mark(αMarker, "αfake1α")
-
-go 1.14
-
-require golang.org/modfile v0.0.0 //@mark(βMarker, "require golang.org/modfile v0.0.0")