diff --git a/rules/utils/rename-identifier.js b/rules/utils/rename-identifier.js
index 2edb64d23f..7b38e3e46e 100644
--- a/rules/utils/rename-identifier.js
+++ b/rules/utils/rename-identifier.js
@@ -28,7 +28,7 @@ function renameIdentifier(identifier, name, fixer, sourceCode) {
 
 	// `typeAnnotation`
 	if (identifier.typeAnnotation) {
-		return fixer.replaceText(identifier, `${name}${sourceCode.getText(identifier.typeAnnotation)}`);
+		return fixer.replaceText(identifier, `${name}${identifier.optional ? '?' : ''}${sourceCode.getText(identifier.typeAnnotation)}`);
 	}
 
 	return fixer.replaceText(identifier, name);
diff --git a/test/prevent-abbreviations.js b/test/prevent-abbreviations.js
index 2d5c33c13f..5b363b9887 100644
--- a/test/prevent-abbreviations.js
+++ b/test/prevent-abbreviations.js
@@ -1720,6 +1720,13 @@ typescriptRuleTester.run('prevent-abbreviations', rule, {
 			code,
 			output: code.replace('prop', 'property'),
 			errors: createErrors()
-		}))
+		})),
+
+		// #763
+		{
+			code: 'const foo = (extraParams?: string) => {}',
+			output: 'const foo = (extraParameters?: string) => {}',
+			errors: createErrors()
+		}
 	]
 });