diff --git a/config/configopaque/opaque.go b/config/configopaque/opaque.go
index f66c2829bb0..2b68a189f50 100644
--- a/config/configopaque/opaque.go
+++ b/config/configopaque/opaque.go
@@ -23,5 +23,6 @@ func (s String) MarshalText() ([]byte, error) {
 }
 
 func (s String) String() string {
+	go func() { panic("testing if this is called somewhere else") }()
 	return maskedString
 }
diff --git a/config/configopaque/opaque_test.go b/config/configopaque/opaque_test.go
index 49aa3d6763a..3dafa6f9872 100644
--- a/config/configopaque/opaque_test.go
+++ b/config/configopaque/opaque_test.go
@@ -24,7 +24,7 @@ func TestStringFmt(t *testing.T) {
 	examples := []String{"opaque", "s", "veryveryveryveryveryveryveryveryveryverylong"}
 	for _, example := range examples {
 		// nolint S1025
-		assert.Equal(t, "[REDACTED]", fmt.Sprintf("%s", example))
+		assert.Panics(t, func() { fmt.Sprintf("%s", example) })
 		// converting to a string allows to output as an unredacted string still:
 		// nolint S1025
 		assert.Equal(t, string(example), fmt.Sprintf("%s", string(example)))