diff --git a/vcs/src/main/java/org/openjdk/skara/vcs/hg/HgRepository.java b/vcs/src/main/java/org/openjdk/skara/vcs/hg/HgRepository.java
index 90a2efba9..f4613b2d7 100644
--- a/vcs/src/main/java/org/openjdk/skara/vcs/hg/HgRepository.java
+++ b/vcs/src/main/java/org/openjdk/skara/vcs/hg/HgRepository.java
@@ -650,7 +650,9 @@ public Hash amend(String message, String authorName, String authorEmail, String
 
     @Override
     public Tag tag(Hash hash, String name, String message, String authorName, String authorEmail) throws IOException {
-        var user = authorName + " <" + authorEmail + ">";
+        var user = authorEmail != null ?
+            authorName + " <" + authorEmail + ">" :
+            authorName;
         try (var p = capture("hg", "tag",
                              "--message", message,
                              "--user", user,
diff --git a/vcs/src/test/java/org/openjdk/skara/vcs/RepositoryTests.java b/vcs/src/test/java/org/openjdk/skara/vcs/RepositoryTests.java
index 2e60e0661..79738c79a 100644
--- a/vcs/src/test/java/org/openjdk/skara/vcs/RepositoryTests.java
+++ b/vcs/src/test/java/org/openjdk/skara/vcs/RepositoryTests.java
@@ -2409,4 +2409,19 @@ void testMergeCommitWithRenamedP0AndModifiedP1(VCS vcs) throws IOException {
             assertEquals(Path.of("README.new"), p1.target().path().get());
         }
     }
+
+    @Test
+    void testMercurialTagWithoutEmail() throws IOException, InterruptedException {
+        try (var dir = new TemporaryDirectory()) {
+            var repo = Repository.init(dir.path(), VCS.HG);
+            var readme = dir.path().resolve("README");
+            Files.write(readme, List.of("Hello, readme!"));
+            repo.add(readme);
+            var head = repo.commit("Add README", "author", "author@openjdk.java.net");
+            var tag = repo.tag(head, "1.0", "Add tag 1.0", "duke", null);
+            var annotated = repo.annotate(tag).orElseThrow();
+            assertEquals("duke", annotated.author().name());
+            assertNull(annotated.author().email());
+        }
+    }
 }