diff --git a/src/uu/uuidgen/src/uuidgen.rs b/src/uu/uuidgen/src/uuidgen.rs
index 4d74bd3c..8e05664d 100644
--- a/src/uu/uuidgen/src/uuidgen.rs
+++ b/src/uu/uuidgen/src/uuidgen.rs
@@ -98,7 +98,7 @@ pub fn uu_app() -> Command {
                 .long(options::NAMESPACE)
                 .action(ArgAction::Set)
                 .value_parser(namespace_from_str)
-                .help("namespace for md5/sha1 - one of: @dns @url @oid @x500"),
+                .help("namespace for md5/sha1 - a UUID or one of: @dns @url @oid @x500"),
         )
         .arg(
             Arg::new(options::NAME)
@@ -132,10 +132,14 @@ fn namespace_from_str(s: &str) -> Result<Uuid, USimpleError> {
         "@url" => Ok(Uuid::NAMESPACE_URL),
         "@oid" => Ok(Uuid::NAMESPACE_OID),
         "@x500" => Ok(Uuid::NAMESPACE_X500),
-        _ => Err(USimpleError {
-            code: 1,
-            message: format!("Invalid namespace {s}."),
-        }),
+        // only the 36-character hyphenated form, like libuuid's uuid_parse()
+        _ => match Uuid::try_parse(s) {
+            Ok(uuid) if s.len() == 36 => Ok(uuid),
+            _ => Err(USimpleError {
+                code: 1,
+                message: format!("Invalid namespace {s}."),
+            }),
+        },
     }
 }
 
diff --git a/tests/by-util/test_uuidgen.rs b/tests/by-util/test_uuidgen.rs
index 91bc4bff..e4000cc8 100644
--- a/tests/by-util/test_uuidgen.rs
+++ b/tests/by-util/test_uuidgen.rs
@@ -61,6 +61,43 @@ fn test_md5_sha1() {
         .stdout_only("34da942e-f4a3-5169-9c65-267d2b22cf11\n");
 }
 
+#[test]
+fn test_uuid_namespace() {
+    // the @dns namespace written out, in both cases
+    new_ucmd!()
+        .args(&[
+            "-m",
+            "-n",
+            "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
+            "-N",
+            "a",
+        ])
+        .succeeds()
+        .stdout_only("4c104dd0-4821-30d5-9ce3-0e7a1f8b7c0d\n");
+    new_ucmd!()
+        .args(&[
+            "-s",
+            "-n",
+            "6BA7B810-9DAD-11D1-80B4-00C04FD430C8",
+            "-N",
+            "a",
+        ])
+        .succeeds()
+        .stdout_only("4f3f2898-69e3-5a0d-820a-c4e87987dbce\n");
+    for namespace in [
+        "{6ba7b810-9dad-11d1-80b4-00c04fd430c8}",
+        "6ba7b8109dad11d180b400c04fd430c8",
+        "urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8",
+        "6ba7b810-9dad-11d1-80b4-00c04fd430c",
+    ] {
+        new_ucmd!()
+            .args(&["-s", "-n", namespace, "-N", "a"])
+            .fails()
+            .code_is(1)
+            .stderr_contains(format!("Invalid namespace {namespace}."));
+    }
+}
+
 #[test]
 fn test_invalid_arg() {
     new_ucmd!().arg("-Z").fails().code_is(1);