diff --git a/package.json b/package.json
index 749ca90..c66f647 100644
--- a/package.json
+++ b/package.json
@@ -75,6 +75,7 @@
     "rxjs": "^7.0.0"
   },
   "dependencies": {
-    "lodash": "^4.17.20"
+    "lodash": "^4.17.20",
+    "pretty-format": "^27.4.2"
   }
 }
diff --git a/src/utils.ts b/src/utils.ts
index 505aa7b..4a238dd 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -8,6 +8,7 @@ import {
 } from 'rxjs';
 import { TestScheduler } from 'rxjs/testing';
 import { isEqual } from 'lodash';
+import { format as prettyFormat } from 'pretty-format';
 import { getTestScheduler } from './scheduler';
 import { TestObservable } from './test-observables';
 import { mapSymbolsToNotifications } from './map-symbols-to-notifications';
@@ -182,13 +183,13 @@ function formatMessage(
   receivedMessages: TestMessages,
 ) {
   return `
-    Expected: ${expectedMarbles},
-    Received: ${receivedMarbles},
+Expected: ${expectedMarbles},
+Received: ${receivedMarbles},
     
-    Expected:
-    ${JSON.stringify(expectedMessages)}
+Expected:
+${prettyFormat(expectedMessages)}
     
-    Received:
-    ${JSON.stringify(receivedMessages)},
+Received:
+${prettyFormat(receivedMessages)}
   `;
 }
diff --git a/yarn.lock b/yarn.lock
index 23fa823..08ca3c6 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1299,6 +1299,17 @@
     "@types/yargs" "^16.0.0"
     chalk "^4.0.0"
 
+"@jest/types@^27.4.2":
+  version "27.4.2"
+  resolved "https://registry.yarnpkg.com/@jest/types/-/types-27.4.2.tgz#96536ebd34da6392c2b7c7737d693885b5dd44a5"
+  integrity sha512-j35yw0PMTPpZsUoOBiuHzr1zTYoad1cVIE0ajEjcrJONxxrko/IRGKkXx3os0Nsi4Hu3+5VmDbVfq5WhG/pWAg==
+  dependencies:
+    "@types/istanbul-lib-coverage" "^2.0.0"
+    "@types/istanbul-reports" "^3.0.0"
+    "@types/node" "*"
+    "@types/yargs" "^16.0.0"
+    chalk "^4.0.0"
+
 "@sinonjs/commons@^1.7.0":
   version "1.8.3"
   resolved "https://registry.yarnpkg.com/@sinonjs/commons/-/commons-1.8.3.tgz#3802ddd21a50a949b6721ddd72da36e67e7f1b2d"
@@ -1496,6 +1507,11 @@ ansi-regex@^5.0.0:
   resolved "https://registry.yarnpkg.com/ansi-regex/-/ansi-regex-5.0.0.tgz#388539f55179bf39339c81af30a654d69f87cb75"
   integrity sha512-bY6fj56OUQ0hU1KjFNDQuJFezqKdrAyFdIevADiqrWHwSlbmBNMHp5ak2f40Pm8JTFyM2mqxkG6ngkHO11f/lg==
 
+ansi-regex@^5.0.1:
+  version "5.0.1"
+  resolved "https://registry.yarnpkg.com/ansi-regex/-/ansi-regex-5.0.1.tgz#082cb2c89c9fe8659a311a53bd6a4dc5301db304"
+  integrity sha512-quJQXlTSUGL2LH9SUXo8VwsY4soanhgo6LNSm84E1LBcE8s3O0wpdiRzyR9z/ZZJMlMWv37qOOb9pdJlMUEKFQ==
+
 ansi-styles@^3.1.0:
   version "3.2.0"
   resolved "https://registry.yarnpkg.com/ansi-styles/-/ansi-styles-3.2.0.tgz#c159b8d5be0f9e5a6f346dab94f16ce022161b88"
@@ -4058,6 +4074,16 @@ pretty-format@^27.0.6:
     ansi-styles "^5.0.0"
     react-is "^17.0.1"
 
+pretty-format@^27.4.2:
+  version "27.4.2"
+  resolved "https://registry.yarnpkg.com/pretty-format/-/pretty-format-27.4.2.tgz#e4ce92ad66c3888423d332b40477c87d1dac1fb8"
+  integrity sha512-p0wNtJ9oLuvgOQDEIZ9zQjZffK7KtyR6Si0jnXULIDwrlNF8Cuir3AZP0hHv0jmKuNN/edOnbMjnzd4uTcmWiw==
+  dependencies:
+    "@jest/types" "^27.4.2"
+    ansi-regex "^5.0.1"
+    ansi-styles "^5.0.0"
+    react-is "^17.0.1"
+
 process-nextick-args@~1.0.6:
   version "1.0.7"
   resolved "https://registry.yarnpkg.com/process-nextick-args/-/process-nextick-args-1.0.7.tgz#150e20b756590ad3f91093f25a4f2ad8bff30ba3"