diff --git a/config/interpolate_test.go b/config/interpolate_test.go
index 5af01841f..2bafe4362 100644
--- a/config/interpolate_test.go
+++ b/config/interpolate_test.go
@@ -299,6 +299,11 @@ func TestDetectVariables(t *testing.T) {
 		Input  string
 		Result []InterpolatedVariable
 	}{
+		{
+			"foo $${var.foo}",
+			nil,
+		},
+
 		{
 			"foo ${var.foo}",
 			[]InterpolatedVariable{