diff --git a/.yarn/versions/7041d864.yml b/.yarn/versions/7041d864.yml
new file mode 100644
index 000000000000..fe14fd26bb1f
--- /dev/null
+++ b/.yarn/versions/7041d864.yml
@@ -0,0 +1,33 @@
+releases:
+  "@yarnpkg/builder": patch
+  "@yarnpkg/cli": patch
+  "@yarnpkg/core": patch
+  "@yarnpkg/doctor": patch
+  "@yarnpkg/nm": patch
+  "@yarnpkg/parsers": patch
+  "@yarnpkg/plugin-compat": patch
+  "@yarnpkg/plugin-constraints": patch
+  "@yarnpkg/plugin-dlx": patch
+  "@yarnpkg/plugin-essentials": patch
+  "@yarnpkg/plugin-exec": patch
+  "@yarnpkg/plugin-file": patch
+  "@yarnpkg/plugin-git": patch
+  "@yarnpkg/plugin-github": patch
+  "@yarnpkg/plugin-http": patch
+  "@yarnpkg/plugin-init": patch
+  "@yarnpkg/plugin-interactive-tools": patch
+  "@yarnpkg/plugin-link": patch
+  "@yarnpkg/plugin-nm": patch
+  "@yarnpkg/plugin-npm": patch
+  "@yarnpkg/plugin-npm-cli": patch
+  "@yarnpkg/plugin-pack": patch
+  "@yarnpkg/plugin-patch": patch
+  "@yarnpkg/plugin-pnp": patch
+  "@yarnpkg/plugin-pnpm": patch
+  "@yarnpkg/plugin-stage": patch
+  "@yarnpkg/plugin-typescript": patch
+  "@yarnpkg/plugin-version": patch
+  "@yarnpkg/plugin-workspace-tools": patch
+  "@yarnpkg/pnpify": patch
+  "@yarnpkg/sdks": patch
+  "@yarnpkg/shell": patch
diff --git a/packages/yarnpkg-parsers/sources/syml.ts b/packages/yarnpkg-parsers/sources/syml.ts
index 498df852d869..db5afceff162 100644
--- a/packages/yarnpkg-parsers/sources/syml.ts
+++ b/packages/yarnpkg-parsers/sources/syml.ts
@@ -91,11 +91,16 @@ function stringifyValue(value: any, indentLevel: number, newLineIfObject: boolea
         ? indent
         : ``;
 
-      if (stringifiedValue.startsWith(`\n`)) {
-        return `${recordIndentation}${stringifiedKey}:${stringifiedValue}`;
-      } else {
-        return `${recordIndentation}${stringifiedKey}: ${stringifiedValue}`;
-      }
+      // Yaml 1.2 spec says that keys over 1024 characters need to be prefixed with ? and the : goes in a new line
+      const keyPart = stringifiedKey.length > 1024
+        ? `? ${stringifiedKey}\n:`
+        : `${stringifiedKey}:`;
+
+      const valuePart = stringifiedValue.startsWith(`\n`)
+        ? stringifiedValue
+        : ` ${stringifiedValue}`;
+
+      return `${recordIndentation}${keyPart}${valuePart}`;
     }).join(indentLevel === 0 ? `\n` : ``) || `\n`;
 
     if (!newLineIfObject) {
diff --git a/packages/yarnpkg-parsers/tests/syml.test.js b/packages/yarnpkg-parsers/tests/syml.test.js
index 259e8413b7b3..f1a307c369ae 100644
--- a/packages/yarnpkg-parsers/tests/syml.test.js
+++ b/packages/yarnpkg-parsers/tests/syml.test.js
@@ -1,4 +1,4 @@
-import {parseSyml} from '@yarnpkg/parsers';
+import {parseSyml, stringifySyml} from '@yarnpkg/parsers';
 
 describe(`Syml parser`, () => {
   it(`shouldn't confuse old-style values with new-style keys`, () => {
@@ -21,13 +21,25 @@ describe(`Syml parser`, () => {
 
   it(`should merge duplicates`, () => {
     expect(
-      parseSyml(`    
+      parseSyml(`
       "lodash@npm:^4.17.20":
         version: 4.17.20
-      
+
       "lodash@npm:^4.17.20":
         version: 4.17.20
       `),
     ).toEqual({'lodash@npm:^4.17.20': {version: `4.17.20`}});
   });
 });
+
+describe(`Syml stringifyer`, () => {
+  it(`stringifies an object`, () => {
+    expect(stringifySyml({foo: {bar: `true`, baz: `quux`}})).toEqual(`foo:\n  bar: true\n  baz: quux\n`);
+  });
+
+  it(`stringifies an object with a long key with yaml 1.2 spec`, () => {
+    const longKey = `a`.repeat(1025); // long key is a string of length > 1024
+    expect(stringifySyml({[longKey]: {bar: `true`, baz: `quux`}})).toEqual(`? ${longKey}\n:\n  bar: true\n  baz: quux\n`);
+    expect(stringifySyml({[longKey]: {[longKey]: `quux`, baz: `quux`}})).toEqual(`? ${longKey}\n:\n  ? ${longKey}\n: quux\n  baz: quux\n`);
+  });
+});