diff --git a/lib/serializer.js b/lib/serializer.js
index 0f4dde76..d8ff4b87 100644
--- a/lib/serializer.js
+++ b/lib/serializer.js
@@ -1,5 +1,8 @@
 'use strict'
 
+// eslint-disable-next-line
+const STR_ESCAPE = /[\u0000-\u001f\u0022\u005c\ud800-\udfff]/
+
 module.exports = class Serializer {
   constructor (options) {
     switch (options && options.rounding) {
@@ -116,7 +119,7 @@ module.exports = class Serializer {
         }
       }
       return (last === -1 && ('"' + str + '"')) || ('"' + result + str.slice(last) + '"')
-    } else if (len < 5000 && str.isWellFormed()) {
+    } else if (len < 5000 && STR_ESCAPE.test(str) === false) {
       // Only use the regular expression for shorter input. The overhead is otherwise too much.
       return '"' + str + '"'
     } else {
diff --git a/test/issue-793.test.js b/test/issue-793.test.js
new file mode 100644
index 00000000..0fd5681e
--- /dev/null
+++ b/test/issue-793.test.js
@@ -0,0 +1,107 @@
+'use strict'
+
+const { test } = require('node:test')
+
+const build = require('..')
+
+test('serialize string with newlines - issue #793', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      message: {
+        type: 'string'
+      }
+    }
+  }
+
+  const input = {
+    message: `This is a string
+with multiple
+newlines in it
+Foo`
+  }
+
+  const stringify = build(schema)
+  const output = stringify(input)
+
+  // The output should be valid JSON
+  t.assert.doesNotThrow(() => {
+    JSON.parse(output)
+  }, 'JSON output should be parseable')
+
+  // The parsed output should match the input
+  const parsed = JSON.parse(output)
+  t.assert.equal(parsed.message, input.message)
+})
+
+test('serialize string with various newline characters - issue #793', (t) => {
+  t.plan(4)
+
+  const schema = {
+    type: 'string'
+  }
+
+  const stringify = build(schema)
+
+  // Test \n (line feed)
+  const inputLF = 'line1\nline2'
+  const outputLF = stringify(inputLF)
+  t.assert.equal(JSON.parse(outputLF), inputLF)
+
+  // Test \r (carriage return)
+  const inputCR = 'line1\rline2'
+  const outputCR = stringify(inputCR)
+  t.assert.equal(JSON.parse(outputCR), inputCR)
+
+  // Test \r\n (CRLF)
+  const inputCRLF = 'line1\r\nline2'
+  const outputCRLF = stringify(inputCRLF)
+  t.assert.equal(JSON.parse(outputCRLF), inputCRLF)
+
+  // Test mixed newlines
+  const inputMixed = 'line1\nline2\rline3\r\nline4'
+  const outputMixed = stringify(inputMixed)
+  t.assert.equal(JSON.parse(outputMixed), inputMixed)
+})
+
+test('serialize object with newlines in multiple properties - issue #793', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      message: {
+        type: 'string'
+      },
+      description: {
+        type: 'string'
+      },
+      timestamp: {
+        type: 'string'
+      }
+    }
+  }
+
+  const input = {
+    message: `This is a string
+with multiple
+newlines in it
+Foo`,
+    description: 'This JSON response contains a field with newline characters',
+    timestamp: new Date().toISOString()
+  }
+
+  const stringify = build(schema)
+  const output = stringify(input)
+
+  // The output should be valid JSON
+  t.assert.doesNotThrow(() => {
+    JSON.parse(output)
+  }, 'JSON output should be parseable')
+
+  // The parsed output should match the input
+  const parsed = JSON.parse(output)
+  t.assert.deepEqual(parsed, input)
+})
diff --git a/test/issue-794.test.js b/test/issue-794.test.js
new file mode 100644
index 00000000..dda9a6c7
--- /dev/null
+++ b/test/issue-794.test.js
@@ -0,0 +1,177 @@
+'use strict'
+
+const { test } = require('node:test')
+
+const build = require('..')
+
+test('serialize string with quotes - issue #794', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      message: {
+        type: 'string'
+      }
+    }
+  }
+
+  const input = {
+    message: 'Error: Property "name" is required'
+  }
+
+  const stringify = build(schema)
+  const output = stringify(input)
+
+  // The output should be valid JSON
+  t.assert.doesNotThrow(() => {
+    JSON.parse(output)
+  }, 'JSON output should be parseable')
+
+  // The parsed output should match the input
+  const parsed = JSON.parse(output)
+  t.assert.equal(parsed.message, input.message)
+})
+
+test('serialize string with various quote types - issue #794', (t) => {
+  t.plan(6)
+
+  const schema = {
+    type: 'string'
+  }
+
+  const stringify = build(schema)
+
+  // Test double quotes
+  const inputDoubleQuotes = 'Property "name" is required'
+  const outputDoubleQuotes = stringify(inputDoubleQuotes)
+  t.assert.doesNotThrow(() => JSON.parse(outputDoubleQuotes))
+  t.assert.equal(JSON.parse(outputDoubleQuotes), inputDoubleQuotes)
+
+  // Test single quotes (should be fine but test for completeness)
+  const inputSingleQuotes = "Property 'name' is required"
+  const outputSingleQuotes = stringify(inputSingleQuotes)
+  t.assert.doesNotThrow(() => JSON.parse(outputSingleQuotes))
+  t.assert.equal(JSON.parse(outputSingleQuotes), inputSingleQuotes)
+
+  // Test mixed quotes
+  const inputMixedQuotes = 'Error: "Property \'name\' is required"'
+  const outputMixedQuotes = stringify(inputMixedQuotes)
+  t.assert.doesNotThrow(() => JSON.parse(outputMixedQuotes))
+  t.assert.equal(JSON.parse(outputMixedQuotes), inputMixedQuotes)
+})
+
+test('serialize error-like object with quotes in message - issue #794', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      error: {
+        type: 'object',
+        properties: {
+          message: {
+            type: 'string'
+          },
+          code: {
+            type: 'string'
+          }
+        }
+      }
+    }
+  }
+
+  const input = {
+    error: {
+      message: 'Validation failed: Property "email" must be a valid email address',
+      code: 'VALIDATION_ERROR'
+    }
+  }
+
+  const stringify = build(schema)
+  const output = stringify(input)
+
+  // The output should be valid JSON
+  t.assert.doesNotThrow(() => {
+    JSON.parse(output)
+  }, 'JSON output should be parseable')
+
+  // The parsed output should match the input
+  const parsed = JSON.parse(output)
+  t.assert.deepEqual(parsed, input)
+})
+
+test('serialize validation errors array with quotes - issue #794', (t) => {
+  t.plan(2)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      errors: {
+        type: 'array',
+        items: {
+          type: 'object',
+          properties: {
+            message: {
+              type: 'string'
+            },
+            field: {
+              type: 'string'
+            }
+          }
+        }
+      }
+    }
+  }
+
+  const input = {
+    errors: [
+      {
+        message: 'Property "name" is required',
+        field: 'name'
+      },
+      {
+        message: 'Property "email" must be a valid email address',
+        field: 'email'
+      },
+      {
+        message: 'Value must be between "1" and "100"',
+        field: 'age'
+      }
+    ]
+  }
+
+  const stringify = build(schema)
+  const output = stringify(input)
+
+  // The output should be valid JSON
+  t.assert.doesNotThrow(() => {
+    JSON.parse(output)
+  }, 'JSON output should be parseable')
+
+  // The parsed output should match the input
+  const parsed = JSON.parse(output)
+  t.assert.deepEqual(parsed, input)
+})
+
+test('serialize string with backslashes and quotes - issue #794', (t) => {
+  t.plan(4)
+
+  const schema = {
+    type: 'string'
+  }
+
+  const stringify = build(schema)
+
+  // Test backslashes
+  const inputBackslash = 'Path: C:\\Users\\test\\file.json'
+  const outputBackslash = stringify(inputBackslash)
+  t.assert.doesNotThrow(() => JSON.parse(outputBackslash))
+  t.assert.equal(JSON.parse(outputBackslash), inputBackslash)
+
+  // Test combination of backslashes and quotes
+  const inputMixed = 'Error: Could not find file "C:\\Users\\test\\config.json"'
+  const outputMixed = stringify(inputMixed)
+  t.assert.doesNotThrow(() => JSON.parse(outputMixed))
+  t.assert.equal(JSON.parse(outputMixed), inputMixed)
+})