diff --git a/README.md b/README.md
index df54e7a0..471c153f 100644
--- a/README.md
+++ b/README.md
@@ -56,6 +56,7 @@ const semverCompareLoose = require('semver/functions/compare-loose')
 const semverCompareBuild = require('semver/functions/compare-build')
 const semverSort = require('semver/functions/sort')
 const semverRsort = require('semver/functions/rsort')
+const semverIdentifier = require('semver/functions/identifier')
 
 // low-level comparators between versions
 const semverGt = require('semver/functions/gt')
@@ -400,6 +401,7 @@ strings that they parse.
   or comparators intersect.
 * `parse(v)`: Attempt to parse a string as a semantic version, returning either
   a `SemVer` object or `null`.
+* `identifier(v)`: Return a valid prerelease identifier, or null if it's not valid.
 
 ### Comparison
 
diff --git a/functions/identifier.js b/functions/identifier.js
new file mode 100644
index 00000000..ae4b480c
--- /dev/null
+++ b/functions/identifier.js
@@ -0,0 +1,10 @@
+const {t, src} = require('../internal/re')
+const identifier = (version) => {
+    const split = version.split('\.');
+    const valid = split.every(part => new RegExp(`^${src[t.PRERELEASEIDENTIFIER]}$`).test(part));
+    if (!valid) {
+        return null;
+    }
+    return version;
+}
+module.exports = identifier
diff --git a/index.js b/index.js
index 4a342c6a..5fe844f5 100644
--- a/index.js
+++ b/index.js
@@ -26,6 +26,7 @@ const gte = require('./functions/gte')
 const lte = require('./functions/lte')
 const cmp = require('./functions/cmp')
 const coerce = require('./functions/coerce')
+const identifier = require('./functions/identifier')
 const Comparator = require('./classes/comparator')
 const Range = require('./classes/range')
 const satisfies = require('./functions/satisfies')
@@ -64,6 +65,7 @@ module.exports = {
   lte,
   cmp,
   coerce,
+  identifier,
   Comparator,
   Range,
   satisfies,
@@ -85,4 +87,4 @@ module.exports = {
   SEMVER_SPEC_VERSION: constants.SEMVER_SPEC_VERSION,
   compareIdentifiers: identifiers.compareIdentifiers,
   rcompareIdentifiers: identifiers.rcompareIdentifiers,
-}
+}
\ No newline at end of file
diff --git a/test/functions/identifier.js b/test/functions/identifier.js
new file mode 100644
index 00000000..0e121f8c
--- /dev/null
+++ b/test/functions/identifier.js
@@ -0,0 +1,10 @@
+const {test} = require('tap')
+const identifier = require('../../functions/identifier.js')
+
+test('identifier tests', t => {
+    t.equal(identifier('hotfix-410'), 'hotfix-410')
+    t.equal(identifier('hotfix/410'), null)
+    t.equal(identifier('123.123.123'), '123.123.123')
+    t.equal(identifier('007.james.bond'), null)
+    t.end()
+})