diff --git a/devtools/client/webconsole/test/browser_webconsole_output_06.js b/devtools/client/webconsole/test/browser_webconsole_output_06.js
index 9bcfce9082d1..ad69b390861b 100644
--- a/devtools/client/webconsole/test/browser_webconsole_output_06.js
+++ b/devtools/client/webconsole/test/browser_webconsole_output_06.js
@@ -198,7 +198,7 @@ var inputTests = [
   // 21
   {
     input: '({0: "a", 1: "b", length: 1})',
-    output: 'Object { 1: "b", length: 1, 1 more\u2026 }',
+    output: 'Object { 0: "a", 1: "b", length: 1 }',
     printOutput: "[object Object]",
     inspectable: true,
     variablesViewLabel: "Object",
@@ -225,7 +225,7 @@ var inputTests = [
   // 24
   {
     input: '({0: "a", 2: "b", length: 2})',
-    output: 'Object { 2: "b", length: 2, 1 more\u2026 }',
+    output: 'Object { 0: "a", 2: "b", length: 2 }',
     printOutput: "[object Object]",
     inspectable: true,
     variablesViewLabel: "Object",
@@ -243,7 +243,7 @@ var inputTests = [
   // 26
   {
     input: '({0: "a", b: "b", length: 1})',
-    output: 'Object { b: "b", length: 1, 1 more\u2026 }',
+    output: 'Object { 0: "a", b: "b", length: 1 }',
     printOutput: "[object Object]",
     inspectable: true,
     variablesViewLabel: "Object",
@@ -252,7 +252,7 @@ var inputTests = [
   // 27
   {
     input: '({0: "a", b: "b", length: 2})',
-    output: 'Object { b: "b", length: 2, 1 more\u2026 }',
+    output: 'Object { 0: "a", b: "b", length: 2 }',
     printOutput: "[object Object]",
     inspectable: true,
     variablesViewLabel: "Object",
diff --git a/devtools/server/actors/object.js b/devtools/server/actors/object.js
index 6816338c737e..1f417b951593 100644
--- a/devtools/server/actors/object.js
+++ b/devtools/server/actors/object.js
@@ -1090,7 +1090,7 @@ function enumWeakSetEntries(objectActor) {
  * having customized output. This object holds arrays mapped by
  * Debugger.Object.prototype.class.
  *
- * In each array you can add functions that take two
+ * In each array you can add functions that take three
  * arguments:
  *   - the ObjectActor instance and its hooks to make a preview for,
  *   - the grip object being prepared for the client,
@@ -1102,16 +1102,16 @@ function enumWeakSetEntries(objectActor) {
  * information for the debugger object, or true otherwise.
  */
 DebuggerServer.ObjectActorPreviewers = {
-  String: [function (objectActor, grip) {
-    return wrappedPrimitivePreviewer("String", String, objectActor, grip);
+  String: [function (objectActor, grip, rawObj) {
+    return wrappedPrimitivePreviewer("String", String, objectActor, grip, rawObj);
   }],
 
-  Boolean: [function (objectActor, grip) {
-    return wrappedPrimitivePreviewer("Boolean", Boolean, objectActor, grip);
+  Boolean: [function (objectActor, grip, rawObj) {
+    return wrappedPrimitivePreviewer("Boolean", Boolean, objectActor, grip, rawObj);
   }],
 
-  Number: [function (objectActor, grip) {
-    return wrappedPrimitivePreviewer("Number", Number, objectActor, grip);
+  Number: [function (objectActor, grip, rawObj) {
+    return wrappedPrimitivePreviewer("Number", Number, objectActor, grip, rawObj);
   }],
 
   Function: [function ({obj, hooks}, grip) {
@@ -1379,17 +1379,16 @@ DebuggerServer.ObjectActorPreviewers = {
  *        The result grip to fill in
  * @return Booolean true if the object was handled, false otherwise
  */
-function wrappedPrimitivePreviewer(className, classObj, objectActor, grip) {
+function wrappedPrimitivePreviewer(className, classObj, objectActor, grip, rawObj) {
   let {obj, hooks} = objectActor;
 
   if (!obj.proto || obj.proto.class != className) {
     return false;
   }
 
-  let raw = obj.unsafeDereference();
   let v = null;
   try {
-    v = classObj.prototype.valueOf.call(raw);
+    v = classObj.prototype.valueOf.call(rawObj);
   } catch (ex) {
     // valueOf() can throw if the raw JS object is "misbehaved".
     return false;
@@ -1399,7 +1398,7 @@ function wrappedPrimitivePreviewer(className, classObj, objectActor, grip) {
     return false;
   }
 
-  let canHandle = GenericObject(objectActor, grip, className === "String");
+  let canHandle = GenericObject(objectActor, grip, rawObj, className === "String");
   if (!canHandle) {
     return false;
   }
@@ -1409,7 +1408,7 @@ function wrappedPrimitivePreviewer(className, classObj, objectActor, grip) {
   return true;
 }
 
-function GenericObject(objectActor, grip, specialStringBehavior = false) {
+function GenericObject(objectActor, grip, rawObj, specialStringBehavior = false) {
   let {obj, hooks} = objectActor;
   if (grip.preview || grip.displayString || hooks.getGripDepth() > 1) {
     return false;
@@ -1859,7 +1858,9 @@ DebuggerServer.ObjectActorPreviewers.Object = [
     return true;
   },
 
-  GenericObject,
+  function Object(objectActor, grip, rawObj) {
+    return GenericObject(objectActor, grip, rawObj, /* specialStringBehavior = */ false);
+  },
 ];
 
 /**