diff --git a/lib/assertions/is-map.test.js b/lib/assertions/is-map.test.js
index 1d54db78..130672a4 100644
--- a/lib/assertions/is-map.test.js
+++ b/lib/assertions/is-map.test.js
@@ -133,7 +133,7 @@ describe("refute.isMap", function() {
                 assert.equal(error.code, "ERR_ASSERTION");
                 assert.equal(
                     error.message,
-                    "[refute.isMap] Expected [Map] {  } not to be a Map"
+                    "[refute.isMap] Expected Map [] not to be a Map"
                 );
                 assert.equal(error.name, "AssertionError");
                 assert.equal(error.operator, "refute.isMap");
@@ -175,7 +175,7 @@ describe("refute.isMap", function() {
                     error.message,
                     "[refute.isMap] " +
                         message +
-                        ": Expected [Map] {  } not to be a Map"
+                        ": Expected Map [] not to be a Map"
                 );
                 assert.equal(error.name, "AssertionError");
                 assert.equal(error.operator, "refute.isMap");
diff --git a/lib/assertions/is-weak-map.test.js b/lib/assertions/is-weak-map.test.js
index 64677a29..f530c674 100644
--- a/lib/assertions/is-weak-map.test.js
+++ b/lib/assertions/is-weak-map.test.js
@@ -17,7 +17,7 @@ describe("assert.isWeakMap", function() {
                 assert.equal(error.code, "ERR_ASSERTION");
                 assert.equal(
                     error.message,
-                    "[assert.isWeakMap] Expected [Map] {  } to be a WeakMap"
+                    "[assert.isWeakMap] Expected Map [] to be a WeakMap"
                 );
                 assert.equal(error.name, "AssertionError");
                 assert.equal(error.operator, "assert.isWeakMap");
diff --git a/package-lock.json b/package-lock.json
index 8ef49973..c3bc6c1e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -154,22 +154,22 @@
       }
     },
     "@sinonjs/formatio": {
-      "version": "3.2.2",
-      "resolved": "https://registry.npmjs.org/@sinonjs/formatio/-/formatio-3.2.2.tgz",
-      "integrity": "sha512-B8SEsgd8gArBLMD6zpRw3juQ2FVSsmdd7qlevyDqzS9WTCtvF55/gAL+h6gue8ZvPYcdiPdvueM/qm//9XzyTQ==",
+      "version": "4.0.1",
+      "resolved": "https://registry.npmjs.org/@sinonjs/formatio/-/formatio-4.0.1.tgz",
+      "integrity": "sha512-asIdlLFrla/WZybhm0C8eEzaDNNrzymiTqHMeJl6zPW2881l3uuVRpm0QlRQEjqYWv6CcKMGYME3LbrLJsORBw==",
       "requires": {
         "@sinonjs/commons": "^1",
-        "@sinonjs/samsam": "^3.1.0"
+        "@sinonjs/samsam": "^4.2.0"
       }
     },
     "@sinonjs/samsam": {
-      "version": "3.3.3",
-      "resolved": "https://registry.npmjs.org/@sinonjs/samsam/-/samsam-3.3.3.tgz",
-      "integrity": "sha512-bKCMKZvWIjYD0BLGnNrxVuw4dkWCYsLqFOUWw8VgKF/+5Y+mE7LfHWPIYoDXowH+3a9LsWDMo0uAP8YDosPvHQ==",
+      "version": "4.2.0",
+      "resolved": "https://registry.npmjs.org/@sinonjs/samsam/-/samsam-4.2.0.tgz",
+      "integrity": "sha512-yG7QbUz38ZPIegfuSMEcbOo0kkLGmPa8a0Qlz4dk7+cXYALDScWjIZzAm/u2+Frh+bcdZF6wZJZwwuJjY0WAjA==",
       "requires": {
-        "@sinonjs/commons": "^1.3.0",
+        "@sinonjs/commons": "^1.6.0",
         "array-from": "^2.1.1",
-        "lodash": "^4.17.15"
+        "lodash.get": "^4.4.2"
       }
     },
     "@sinonjs/text-encoding": {
@@ -2253,7 +2253,8 @@
     "lodash": {
       "version": "4.17.15",
       "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.15.tgz",
-      "integrity": "sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A=="
+      "integrity": "sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==",
+      "dev": true
     },
     "lodash.flattendeep": {
       "version": "4.4.0",
@@ -2261,6 +2262,11 @@
       "integrity": "sha1-+wMJF/hqMTTlvJvsDWngAT3f7bI=",
       "dev": true
     },
+    "lodash.get": {
+      "version": "4.4.2",
+      "resolved": "https://registry.npmjs.org/lodash.get/-/lodash.get-4.4.2.tgz",
+      "integrity": "sha1-LRd/ZS+jHpObRDjVNBSZ36OCXpk="
+    },
     "lodash.includes": {
       "version": "4.3.0",
       "resolved": "https://registry.npmjs.org/lodash.includes/-/lodash.includes-4.3.0.tgz",
@@ -2582,6 +2588,29 @@
         "just-extend": "^4.0.2",
         "lolex": "^4.1.0",
         "path-to-regexp": "^1.7.0"
+      },
+      "dependencies": {
+        "@sinonjs/formatio": {
+          "version": "3.2.2",
+          "resolved": "https://registry.npmjs.org/@sinonjs/formatio/-/formatio-3.2.2.tgz",
+          "integrity": "sha512-B8SEsgd8gArBLMD6zpRw3juQ2FVSsmdd7qlevyDqzS9WTCtvF55/gAL+h6gue8ZvPYcdiPdvueM/qm//9XzyTQ==",
+          "dev": true,
+          "requires": {
+            "@sinonjs/commons": "^1",
+            "@sinonjs/samsam": "^3.1.0"
+          }
+        },
+        "@sinonjs/samsam": {
+          "version": "3.3.3",
+          "resolved": "https://registry.npmjs.org/@sinonjs/samsam/-/samsam-3.3.3.tgz",
+          "integrity": "sha512-bKCMKZvWIjYD0BLGnNrxVuw4dkWCYsLqFOUWw8VgKF/+5Y+mE7LfHWPIYoDXowH+3a9LsWDMo0uAP8YDosPvHQ==",
+          "dev": true,
+          "requires": {
+            "@sinonjs/commons": "^1.3.0",
+            "array-from": "^2.1.1",
+            "lodash": "^4.17.15"
+          }
+        }
       }
     },
     "node-environment-flags": {
@@ -3373,6 +3402,29 @@
         "lolex": "^4.2.0",
         "nise": "^1.5.2",
         "supports-color": "^5.5.0"
+      },
+      "dependencies": {
+        "@sinonjs/formatio": {
+          "version": "3.2.2",
+          "resolved": "https://registry.npmjs.org/@sinonjs/formatio/-/formatio-3.2.2.tgz",
+          "integrity": "sha512-B8SEsgd8gArBLMD6zpRw3juQ2FVSsmdd7qlevyDqzS9WTCtvF55/gAL+h6gue8ZvPYcdiPdvueM/qm//9XzyTQ==",
+          "dev": true,
+          "requires": {
+            "@sinonjs/commons": "^1",
+            "@sinonjs/samsam": "^3.1.0"
+          }
+        },
+        "@sinonjs/samsam": {
+          "version": "3.3.3",
+          "resolved": "https://registry.npmjs.org/@sinonjs/samsam/-/samsam-3.3.3.tgz",
+          "integrity": "sha512-bKCMKZvWIjYD0BLGnNrxVuw4dkWCYsLqFOUWw8VgKF/+5Y+mE7LfHWPIYoDXowH+3a9LsWDMo0uAP8YDosPvHQ==",
+          "dev": true,
+          "requires": {
+            "@sinonjs/commons": "^1.3.0",
+            "array-from": "^2.1.1",
+            "lodash": "^4.17.15"
+          }
+        }
       }
     },
     "slash": {
diff --git a/package.json b/package.json
index a1a1ba04..fe5f577a 100644
--- a/package.json
+++ b/package.json
@@ -29,8 +29,8 @@
   },
   "dependencies": {
     "@sinonjs/commons": "^1.4.0",
-    "@sinonjs/formatio": "^3.1.0",
-    "@sinonjs/samsam": "^3.3.0",
+    "@sinonjs/formatio": "^4.0.1",
+    "@sinonjs/samsam": "^4.2.0",
     "array-from": "2.1.1",
     "bane": "^1.x",
     "lodash.includes": "^4.3.0",