diff --git a/lib/sinon.js b/lib/sinon.js
index 8f1dedc8c..19ffde756 100644
--- a/lib/sinon.js
+++ b/lib/sinon.js
@@ -4,7 +4,6 @@ var behavior = require("./sinon/behavior");
 var createSandbox = require("./sinon/create-sandbox");
 var extend = require("./sinon/util/core/extend");
 var fakeTimers = require("./sinon/util/fake-timers");
-var format = require("./sinon/util/core/format");
 var nise = require("nise");
 var Sandbox = require("./sinon/sandbox");
 var stub = require("./sinon/stub");
@@ -19,8 +18,6 @@ var apiMethods = {
     expectation: require("./sinon/mock-expectation"),
     defaultConfig: require("./sinon/util/core/default-config"),
 
-    setFormatter: format.setFormatter,
-
     // fake timers
     timers: fakeTimers.timers,
 
diff --git a/lib/sinon/assert.js b/lib/sinon/assert.js
index 5af71bbb6..7d36b41c1 100644
--- a/lib/sinon/assert.js
+++ b/lib/sinon/assert.js
@@ -5,7 +5,7 @@ var calledInOrder = require("@sinonjs/commons").calledInOrder;
 var createMatcher = require("@sinonjs/samsam").createMatcher;
 var orderByFirstCall = require("@sinonjs/commons").orderByFirstCall;
 var timesInWords = require("./util/core/times-in-words");
-var format = require("./util/core/format");
+var inspect = require("util").inspect;
 var stringSlice = require("@sinonjs/commons").prototypes.string.slice;
 var globalObject = require("@sinonjs/commons").global;
 
@@ -162,7 +162,7 @@ function createAssertObject() {
             var msg;
             if (typeof count !== "number") {
                 msg =
-                    `expected ${format(count)} to be a number ` +
+                    `expected ${inspect(count)} to be a number ` +
                     `but was of type ${typeof count}`;
                 failAssertion(this, msg);
             } else if (method.callCount !== count) {
@@ -206,8 +206,8 @@ function createAssertObject() {
             } else {
                 var formatted = [
                     "expected value to match",
-                    `    expected = ${format(expectation)}`,
-                    `    actual = ${format(actual)}`,
+                    `    expected = ${inspect(expectation)}`,
+                    `    actual = ${inspect(actual)}`,
                 ];
 
                 failAssertion(this, join(formatted, "\n"));
diff --git a/lib/sinon/mock-expectation.js b/lib/sinon/mock-expectation.js
index ffef5700b..bf9aeb584 100644
--- a/lib/sinon/mock-expectation.js
+++ b/lib/sinon/mock-expectation.js
@@ -9,7 +9,7 @@ var match = require("@sinonjs/samsam").createMatcher;
 var stub = require("./stub");
 var assert = require("./assert");
 var deepEqual = require("@sinonjs/samsam").deepEqual;
-var format = require("./util/core/format");
+var inspect = require("util").inspect;
 var valueToString = require("@sinonjs/commons").valueToString;
 
 var every = arrayProto.every;
@@ -166,7 +166,7 @@ var mockExpectation = {
 
         if (!args) {
             mockExpectation.fail(
-                `${this.method} received no arguments, expected ${format(
+                `${this.method} received no arguments, expected ${inspect(
                     expectedArguments
                 )}`
             );
@@ -174,9 +174,9 @@ var mockExpectation = {
 
         if (args.length < expectedArguments.length) {
             mockExpectation.fail(
-                `${this.method} received too few arguments (${format(
+                `${this.method} received too few arguments (${inspect(
                     args
-                )}), expected ${format(expectedArguments)}`
+                )}), expected ${inspect(expectedArguments)}`
             );
         }
 
@@ -185,9 +185,9 @@ var mockExpectation = {
             args.length !== expectedArguments.length
         ) {
             mockExpectation.fail(
-                `${this.method} received too many arguments (${format(
+                `${this.method} received too many arguments (${inspect(
                     args
-                )}), expected ${format(expectedArguments)}`
+                )}), expected ${inspect(expectedArguments)}`
             );
         }
 
@@ -196,7 +196,7 @@ var mockExpectation = {
             function (expectedArgument, i) {
                 if (!verifyMatcher(expectedArgument, args[i])) {
                     mockExpectation.fail(
-                        `${this.method} received wrong arguments ${format(
+                        `${this.method} received wrong arguments ${inspect(
                             args
                         )}, didn't match ${String(expectedArguments)}`
                     );
@@ -204,9 +204,9 @@ var mockExpectation = {
 
                 if (!deepEqual(args[i], expectedArgument)) {
                     mockExpectation.fail(
-                        `${this.method} received wrong arguments ${format(
+                        `${this.method} received wrong arguments ${inspect(
                             args
-                        )}, expected ${format(expectedArguments)}`
+                        )}, expected ${inspect(expectedArguments)}`
                     );
                 }
             },
diff --git a/lib/sinon/proxy-call.js b/lib/sinon/proxy-call.js
index 899579fc1..87c1df44f 100644
--- a/lib/sinon/proxy-call.js
+++ b/lib/sinon/proxy-call.js
@@ -4,7 +4,7 @@ var arrayProto = require("@sinonjs/commons").prototypes.array;
 var match = require("@sinonjs/samsam").createMatcher;
 var deepEqual = require("@sinonjs/samsam").deepEqual;
 var functionName = require("@sinonjs/commons").functionName;
-var sinonFormat = require("./util/core/format");
+var inspect = require("util").inspect;
 var valueToString = require("@sinonjs/commons").valueToString;
 
 var concat = arrayProto.concat;
@@ -208,13 +208,13 @@ var callProto = {
         }
 
         formattedArgs = map(this.args, function (arg) {
-            return sinonFormat(arg);
+            return inspect(arg);
         });
 
         callStr = `${callStr + join(formattedArgs, ", ")})`;
 
         if (typeof this.returnValue !== "undefined") {
-            callStr += ` => ${sinonFormat(this.returnValue)}`;
+            callStr += ` => ${inspect(this.returnValue)}`;
         }
 
         if (this.exception) {
diff --git a/lib/sinon/proxy.js b/lib/sinon/proxy.js
index 82505c536..1627ff103 100644
--- a/lib/sinon/proxy.js
+++ b/lib/sinon/proxy.js
@@ -6,7 +6,7 @@ var functionToString = require("./util/core/function-to-string");
 var proxyCall = require("./proxy-call");
 var proxyCallUtil = require("./proxy-call-util");
 var proxyInvoke = require("./proxy-invoke");
-var sinonFormat = require("./util/core/format");
+var inspect = require("util").inspect;
 
 var push = arrayProto.push;
 var forEach = arrayProto.forEach;
@@ -126,7 +126,7 @@ var proxyApi = {
             if (typeof formatter === "function") {
                 return String(formatter(spyInstance, args));
             } else if (!isNaN(parseInt(specifier, 10))) {
-                return sinonFormat(args[specifier - 1]);
+                return inspect(args[specifier - 1]);
             }
 
             return `%${specifier}`;
diff --git a/lib/sinon/spy-formatters.js b/lib/sinon/spy-formatters.js
index 58685453d..f2ddce139 100644
--- a/lib/sinon/spy-formatters.js
+++ b/lib/sinon/spy-formatters.js
@@ -4,7 +4,7 @@ var arrayProto = require("@sinonjs/commons").prototypes.array;
 var color = require("./color");
 var match = require("@sinonjs/samsam").createMatcher;
 var timesInWords = require("./util/core/times-in-words");
-var sinonFormat = require("./util/core/format");
+var inspect = require("util").inspect;
 var jsDiff = require("diff");
 
 var join = arrayProto.join;
@@ -85,7 +85,7 @@ module.exports = {
                 message += "\n";
 
                 var calledArgMessage =
-                    j < calledArgs.length ? sinonFormat(calledArg) : "";
+                    j < calledArgs.length ? inspect(calledArg) : "";
                 if (match.isMatcher(expectedArg)) {
                     message += colorSinonMatchText(
                         expectedArg,
@@ -94,7 +94,7 @@ module.exports = {
                     );
                 } else {
                     var expectedArgMessage =
-                        j < expectedArgs.length ? sinonFormat(expectedArg) : "";
+                        j < expectedArgs.length ? inspect(expectedArg) : "";
                     var diff = jsDiff.diffJson(
                         calledArgMessage,
                         expectedArgMessage
@@ -126,7 +126,7 @@ module.exports = {
         var objects = [];
 
         for (var i = 0, l = spyInstance.callCount; i < l; ++i) {
-            push(objects, sinonFormat(spyInstance.thisValues[i]));
+            push(objects, inspect(spyInstance.thisValues[i]));
         }
 
         return join(objects, ", ");
@@ -135,7 +135,7 @@ module.exports = {
     "*": function (spyInstance, args) {
         return join(
             map(args, function (arg) {
-                return sinonFormat(arg);
+                return inspect(arg);
             }),
             ", "
         );