diff --git a/CHANGELOG.md b/CHANGELOG.md
index caa9256b98..e34cbcd410 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,8 @@
 - **github**: Allow for error handling
 - **cli**: Adds a relevant file path to an error message [#1887](https://github.com/kamilkisiela/graphql-inspector/pull/1887)
 - **cli**: Adds `--left-header` and `--right-header` [#1899](https://github.com/kamilkisiela/graphql-inspector/pull/1899)
-- **core**: add rule to make dangerous changes breaking (`dangerousBreaking`) [#1899](https://github.com/kamilkisiela/graphql-inspector/pull/1899)
+- **core**: Add rule to make dangerous changes breaking (`dangerousBreaking`) [#1899](https://github.com/kamilkisiela/graphql-inspector/pull/1899)
+- **core**: Make sure default argument values are printable [#1959](https://github.com/kamilkisiela/graphql-inspector/pull/1959)
 
 ### v2.5.0
 
diff --git a/packages/core/__tests__/utils/string.ts b/packages/core/__tests__/utils/string.ts
new file mode 100644
index 0000000000..ea282387c1
--- /dev/null
+++ b/packages/core/__tests__/utils/string.ts
@@ -0,0 +1,20 @@
+import {safeString} from '../../src/utils/string';
+
+test('scalars', () => {
+  expect(safeString(0)).toBe('0');
+  expect(safeString(42)).toBe('42');
+  expect(safeString(42.42)).toBe('42.42');
+  expect(safeString('42')).toBe('42');
+  expect(safeString('true')).toBe('true');
+  expect(safeString(true)).toBe('true');
+  expect(safeString('false')).toBe('false');
+  expect(safeString(false)).toBe('false');
+});
+
+test('null', () => {
+  expect(safeString(null)).toBe('null');
+});
+
+test('undefined', () => {
+  expect(safeString(undefined)).toBe('undefined');
+});
diff --git a/packages/core/package.json b/packages/core/package.json
index 3a1325ce3d..ce1d6e79d2 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -30,8 +30,12 @@
   },
   "dependencies": {
     "dependency-graph": "0.11.0",
+    "object-inspect": "1.10.3",
     "tslib": "^2.0.0"
   },
+  "devDependencies": {
+    "@types/object-inspect": "1.8.0"
+  },
   "scripts": {
     "prepack": "bob prepack"
   }
diff --git a/packages/core/src/utils/string.ts b/packages/core/src/utils/string.ts
index ea76c5fab4..a2f1b166fe 100644
--- a/packages/core/src/utils/string.ts
+++ b/packages/core/src/utils/string.ts
@@ -1,3 +1,5 @@
+import inspect from 'object-inspect';
+
 export interface Target {
   typeId: string;
   value: string;
@@ -75,3 +77,10 @@ function wordLetterPairs(str: string) {
   const pairs = str.toUpperCase().split(' ').map(letterPairs);
   return flattenDeep(pairs);
 }
+
+export function safeString(obj: any) {
+  if (obj != null && typeof obj.toString === 'function') {
+    return `${obj}`;
+  }
+  return inspect(obj);
+}
diff --git a/yarn.lock b/yarn.lock
index b8e08512f9..122e8790b0 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2467,6 +2467,11 @@
   resolved "https://registry.yarnpkg.com/@types/normalize-package-data/-/normalize-package-data-2.4.0.tgz#e486d0d97396d79beedd0a6e33f4534ff6b4973e"
   integrity sha512-f5j5b/Gf71L+dbqxIpQ4Z2WlmI/mPJ0fOkGGmFgtb6sAu97EPczzbS3/tJKxmcYDj55OX6ssqwDAWOHIYDRDGA==
 
+"@types/object-inspect@1.8.0":
+  version "1.8.0"
+  resolved "https://registry.yarnpkg.com/@types/object-inspect/-/object-inspect-1.8.0.tgz#d3a4537b771d06af85bdd2f25d20954433c25c49"
+  integrity sha512-r0xcaoZLwB0qCiR4lw1xZue3T9p8i/JdKslESAwfMEvjHIYK8DhQaV02K6WTJ29ueZOUe9ttscvP2Tv3ujBAHg==
+
 "@types/parse-json@^4.0.0":
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/@types/parse-json/-/parse-json-4.0.0.tgz#2f8bb441434d163b35fb8ffdccd7138927ffb8c0"
@@ -7685,6 +7690,11 @@ object-copy@^0.1.0:
     define-property "^0.2.5"
     kind-of "^3.0.3"
 
+object-inspect@1.10.3:
+  version "1.10.3"
+  resolved "https://registry.yarnpkg.com/object-inspect/-/object-inspect-1.10.3.tgz#c2aa7d2d09f50c99375704f7a0adf24c5782d369"
+  integrity sha512-e5mCJlSH7poANfC8z8S9s9S2IN5/4Zb3aZ33f5s8YqoazCFzNLloLU8r5VCG+G7WoqLvAAZoVMcy3tp/3X0Plw==
+
 object-inspect@^1.7.0, object-inspect@^1.8.0:
   version "1.8.0"
   resolved "https://registry.yarnpkg.com/object-inspect/-/object-inspect-1.8.0.tgz#df807e5ecf53a609cc6bfe93eac3cc7be5b3a9d0"