diff --git a/docs/options.md b/docs/options.md
index b104eb1ee..b4d526560 100644
--- a/docs/options.md
+++ b/docs/options.md
@@ -36,6 +36,7 @@ const defaultOptions = {
   allErrors: false,
   verbose: false,
   discriminator: false, // *
+  unicodeRegExp: true // *
   $comment: false, // *
   formats: {},
   keywords: {},
@@ -167,6 +168,15 @@ Include the reference to the part of the schema (`schema` and `parentSchema`) an
 
 Support [discriminator keyword](./json-schema.md#discriminator) from [OpenAPI specification](https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.1.0.md).
 
+### unicodeRegExp
+
+By default Ajv uses unicode flag "u" with "pattern" and "patternProperties", as per JSON Schema spec. See [RegExp.prototype.unicode](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/unicode) .
+
+Option values:
+
+- `true` (default) - use unicode flag "u".
+- `false` - do not use flag "u".
+
 ### $comment
 
 Log or pass the value of `$comment` keyword to a function.
diff --git a/lib/core.ts b/lib/core.ts
index 40aa56d33..090f0f2ea 100644
--- a/lib/core.ts
+++ b/lib/core.ts
@@ -97,6 +97,7 @@ export interface CurrentOptions {
   allErrors?: boolean
   verbose?: boolean
   discriminator?: boolean
+  unicodeRegExp?: boolean
   $comment?:
     | true
     | ((comment: string, schemaPath?: string, rootSchema?: AnySchemaObject) => unknown)
@@ -212,7 +213,8 @@ type RequiredInstanceOptions = {
     | "messages"
     | "addUsedSchema"
     | "validateSchema"
-    | "validateFormats"]: NonNullable<Options[K]>
+    | "validateFormats"
+    | "unicodeRegExp"]: NonNullable<Options[K]>
 } & {code: InstanceCodeOptions}
 
 export type InstanceOptions = Options & RequiredInstanceOptions
@@ -239,6 +241,7 @@ function requiredOptions(o: Options): RequiredInstanceOptions {
     addUsedSchema: o.addUsedSchema ?? true,
     validateSchema: o.validateSchema ?? true,
     validateFormats: o.validateFormats ?? true,
+    unicodeRegExp: o.unicodeRegExp ?? true,
   }
 }
 
diff --git a/lib/vocabularies/applicator/additionalProperties.ts b/lib/vocabularies/applicator/additionalProperties.ts
index 03ca8080a..bfb511ce5 100644
--- a/lib/vocabularies/applicator/additionalProperties.ts
+++ b/lib/vocabularies/applicator/additionalProperties.ts
@@ -60,7 +60,7 @@ const def: CodeKeywordDefinition & AddedKeywordDefinition = {
         definedProp = nil
       }
       if (patProps.length) {
-        definedProp = or(definedProp, ...patProps.map((p) => _`${usePattern(gen, p)}.test(${key})`))
+        definedProp = or(definedProp, ...patProps.map((p) => _`${usePattern(cxt, p)}.test(${key})`))
       }
       return not(definedProp)
     }
diff --git a/lib/vocabularies/applicator/patternProperties.ts b/lib/vocabularies/applicator/patternProperties.ts
index 25c3e308f..525535438 100644
--- a/lib/vocabularies/applicator/patternProperties.ts
+++ b/lib/vocabularies/applicator/patternProperties.ts
@@ -50,7 +50,7 @@ const def: CodeKeywordDefinition = {
 
     function validateProperties(pat: string): void {
       gen.forIn("key", data, (key) => {
-        gen.if(_`${usePattern(gen, pat)}.test(${key})`, () => {
+        gen.if(_`${usePattern(cxt, pat)}.test(${key})`, () => {
           cxt.subschema(
             {
               keyword: "patternProperties",
diff --git a/lib/vocabularies/code.ts b/lib/vocabularies/code.ts
index 80387c81a..ca1cf5f0a 100644
--- a/lib/vocabularies/code.ts
+++ b/lib/vocabularies/code.ts
@@ -90,11 +90,12 @@ export function callValidateCode(
   return context !== nil ? _`${func}.call(${context}, ${args})` : _`${func}(${args})`
 }
 
-export function usePattern(gen: CodeGen, pattern: string): Name {
+export function usePattern({gen, it: {opts}}: KeywordCxt, pattern: string): Name {
+  const u = opts.unicodeRegExp ? "u" : ""
   return gen.scopeValue("pattern", {
     key: pattern,
-    ref: new RegExp(pattern, "u"),
-    code: _`new RegExp(${pattern}, "u")`,
+    ref: new RegExp(pattern, u),
+    code: _`new RegExp(${pattern}, ${u})`,
   })
 }
 
diff --git a/lib/vocabularies/validation/pattern.ts b/lib/vocabularies/validation/pattern.ts
index 880279f8f..7b27b7d3c 100644
--- a/lib/vocabularies/validation/pattern.ts
+++ b/lib/vocabularies/validation/pattern.ts
@@ -17,8 +17,10 @@ const def: CodeKeywordDefinition = {
   $data: true,
   error,
   code(cxt: KeywordCxt) {
-    const {gen, data, $data, schema, schemaCode} = cxt
-    const regExp = $data ? _`(new RegExp(${schemaCode}, "u"))` : usePattern(gen, schema) // TODO regexp should be wrapped in try/catch
+    const {data, $data, schema, schemaCode, it} = cxt
+    // TODO regexp should be wrapped in try/catchs
+    const u = it.opts.unicodeRegExp ? "u" : ""
+    const regExp = $data ? _`(new RegExp(${schemaCode}, ${u}))` : usePattern(cxt, schema)
     cxt.fail$data(_`!${regExp}.test(${data})`)
   },
 }
diff --git a/spec/options/unicodeRegExp.spec.ts b/spec/options/unicodeRegExp.spec.ts
new file mode 100644
index 000000000..737fa0432
--- /dev/null
+++ b/spec/options/unicodeRegExp.spec.ts
@@ -0,0 +1,67 @@
+import _Ajv from "../ajv"
+import chai from "../chai"
+const should = chai.should()
+
+describe("unicodeRegExp option", () => {
+  const unicodeChar = "\uD83D\uDC4D"
+  const unicodeSchema = {
+    type: "string",
+    pattern: `^[${unicodeChar}]$`,
+  }
+
+  const schemaWithEscape = {
+    type: "string",
+    pattern: "^[\\:]$",
+  }
+
+  const patternPropertiesSchema = {
+    type: "object",
+    patternProperties: {
+      "^\\:.*$": {type: "number"},
+    },
+    additionalProperties: false,
+  }
+
+  describe("= true (default)", () => {
+    const ajv = new _Ajv()
+    it("should fail schema compilation if used invalid (unnecessary) escape sequence for pattern", () => {
+      should.throw(() => {
+        ajv.compile(schemaWithEscape)
+      }, /Invalid escape/)
+    })
+
+    it("should fail schema compilation if used invalid (unnecessary) escape sequence for patternProperties", () => {
+      should.throw(() => {
+        ajv.compile(patternPropertiesSchema)
+      }, /Invalid escape/)
+    })
+
+    it("should validate unicode character", () => {
+      const validate = ajv.compile(unicodeSchema)
+      validate(unicodeChar).should.equal(true)
+    })
+  })
+
+  describe("= false", () => {
+    const ajv = new _Ajv({unicodeRegExp: false})
+    it("should pass schema compilation if used unnecessary escape sequence for pattern", () => {
+      should.not.throw(() => {
+        const validate = ajv.compile(schemaWithEscape)
+        validate(":").should.equal(true)
+      })
+    })
+
+    it("should pass schema compilation if used unnecessary escape sequence for patternProperties", () => {
+      should.not.throw(() => {
+        const validate = ajv.compile(patternPropertiesSchema)
+        validate({":test": 1}).should.equal(true)
+        validate({test: 1}).should.equal(false)
+      })
+    })
+
+    it("should not validate unicode character", () => {
+      const validate = ajv.compile(unicodeSchema)
+      validate(unicodeChar).should.equal(false)
+    })
+  })
+})