diff --git a/packages/base/source/adt/union/derivations/debug-representation.js b/packages/base/source/adt/union/derivations/debug-representation.js
index 229b3dd..29572a5 100644
--- a/packages/base/source/adt/union/derivations/debug-representation.js
+++ b/packages/base/source/adt/union/derivations/debug-representation.js
@@ -49,14 +49,20 @@ const functionToString = (fn) => `[Function${functionNameToString(fn)}]`;
  */
 const nullToString = () => 'null';
 
+/*~
+ * type: (Any) => Bool
+ */
+const isPlainObject = (object) =>
+  !object.toString || (object.toString === Object.prototype.toString);
+
 /*~
  * type: (Null | Object Any) => String
  */
 const objectToString = (object) =>
-    object === null                       ?  nullToString
-  : Array.isArray(object)                 ?  arrayToString
-  : object.toString() === ({}).toString() ?  plainObjectToString
-  : /* otherwise */                          object.toString;
+    object === null          ?  nullToString
+  : Array.isArray(object)    ?  arrayToString
+  : isPlainObject(object)    ?  plainObjectToString
+  : /* otherwise */             object.toString;
 
 
 /*~
diff --git a/packages/base/source/conversions/nullable-to-result.js b/packages/base/source/conversions/nullable-to-result.js
index 6aa48f6..a58777e 100644
--- a/packages/base/source/conversions/nullable-to-result.js
+++ b/packages/base/source/conversions/nullable-to-result.js
@@ -22,7 +22,7 @@ const deprecated = require('folktale/helpers/warn-deprecation');
  *   & (a or None) => Result None a
  */
 const nullableToResult = function(a, givenFallback) {
-  const oldBehaviour = arguments.length < 2;
+  const oldBehaviour = arguments.length < 2;  // eslint-disable-line prefer-rest-params
   if (oldBehaviour) {
     deprecated(`nullableToResult(value) is being deprecated in favour of providing an explicit fallback value.
 nullableToResult(value, fallback) is the new preferred form of this function.
diff --git a/packages/base/source/result/index.js b/packages/base/source/result/index.js
index b14bf8d..f758759 100644
--- a/packages/base/source/result/index.js
+++ b/packages/base/source/result/index.js
@@ -32,7 +32,7 @@ module.exports = {
   fromNullable(aNullable, fallbackValue) {
     const nullableToResult = require('folktale/conversions/nullable-to-result');
 
-    if (arguments.length > 1) {
+    if (arguments.length > 1) {  // eslint-disable-line prefer-rest-params 
       return nullableToResult(aNullable, fallbackValue);
     } else {
       return nullableToResult(aNullable);
diff --git a/test/source/specs/base/adt/union.js b/test/source/specs/base/adt/union.js
index a2c28f8..1dca2bd 100644
--- a/test/source/specs/base/adt/union.js
+++ b/test/source/specs/base/adt/union.js
@@ -214,6 +214,28 @@ describe('ADT: union', () => {
     property('Recursive Values have a string representation', () => {
       return AB.A({rec:AB.A(1)}).toString()  ===  'AB.A({ value: { rec: AB.A({ value: 1 }) } })'
     })
+
+    property('ADTs containing objects with custom .toString get serialised properly', () => {
+      const a = { toString(){ return 'hello' }};
+
+      return AB.A(a).toString() === 'AB.A({ value: hello })'
+    });
+
+    // Issue https://github.com/origamitower/folktale/issues/168
+    property('ADTs containing objects without a .toString get serialised properly', () => {
+      const a = Object.create(null);
+      a.foo = 1;
+
+      return AB.A(a).toString() === 'AB.A({ value: { foo: 1 } })'
+    });
+
+    // Issue https://github.com/origamitower/folktale/issues/167
+    xit('Circular objects get serialised properly', () => {
+      const a = Object.create(null);
+      a.a = a;
+
+      return AB.A(a).toString() === 'AB.A({ value: { a: [Circular] } })'
+    });
   });
   describe('Serialization', () => {
     const AB = union('folktale:AB', {