diff --git a/std/json.d b/std/json.d
index 65adbbe02..61af86a45 100644
--- a/std/json.d
+++ b/std/json.d
@@ -390,14 +390,14 @@ struct JSONValue
     }
 
     /// Implicitly calls $(D toJSON) on this JSONValue.
-    string toString()
+    string toString() const
     {
         return toJSON(&this);
     }
 
     /// Implicitly calls $(D toJSON) on this JSONValue, like $(D toString), but
     /// also passes $(I true) as $(I pretty) argument.
-    string toPrettyString()
+    string toPrettyString() const
     {
         return toJSON(&this, true);
     }
@@ -1066,6 +1066,13 @@ unittest
 }`);
 }
 
+unittest {
+  auto json = `"hello\nworld"`;
+  const jv = parseJSON(json);
+  assert(jv.toString == json);
+  assert(jv.toPrettyString == json);
+}
+
 deprecated unittest
 {
     // Bugzilla 12332