diff --git a/mapbox/services/uploads.py b/mapbox/services/uploads.py
index 94dcd75..66d36b5 100644
--- a/mapbox/services/uploads.py
+++ b/mapbox/services/uploads.py
@@ -1,6 +1,7 @@
 """
 Mapbox Uploads API
 """
+import re
 
 from boto3.session import Session as boto3_session
 from uritemplate import URITemplate
@@ -54,8 +55,12 @@ def _validate_tileset(self, tileset):
         """
         if '.' not in tileset:
             tileset = "{0}.{1}".format(self.username, tileset)
-        if len(tileset) > 64:
-            raise ValidationError('tileset including username must be < 64 char')
+
+        pattern = '^[a-z0-9-_]{1,32}\.[a-z0-9-_]{1,32}$'
+        if not re.match(pattern, tileset, flags=re.IGNORECASE):
+            raise ValidationError(
+                f'tileset {tileset} is invalid, must match r"{pattern}"')
+
         return tileset
 
     def stage(self, fileobj, creds=None, callback=None):
diff --git a/tests/test_upload.py b/tests/test_upload.py
index 9b2ec99..4bb31d9 100644
--- a/tests/test_upload.py
+++ b/tests/test_upload.py
@@ -416,7 +416,7 @@ def ensure_patch(request):
 
     with open('tests/moors.json', 'rb') as src:
         res = mapbox.Uploader(access_token=access_token).upload(
-            src, 'testuser.test1', name='test1', patch=True)
+            src, 'testuser.Test1', name='test1', patch=True)
 
     assert res.status_code == 201
     job = res.json()
@@ -426,8 +426,17 @@ def ensure_patch(request):
 def test_upload_tileset_validation():
     with pytest.raises(mapbox.errors.ValidationError):
         with open('tests/moors.json', 'rb') as src:
+            # limited to 32 chars, try 40
             mapbox.Uploader(access_token=access_token).upload(
-                src, 'a' * 65, name='test1', patch=True)
+                src, 'username.' + 'aA' * 20, name='test1')
+
+
+def test_upload_tileset_validation_specialchar():
+    with pytest.raises(mapbox.errors.ValidationError):
+        with open('tests/moors.json', 'rb') as src:
+            # limited to a-z0-9-_ chars
+            mapbox.Uploader(access_token=access_token).upload(
+                src, 'username.&#!', name='test1')
 
 
 def test_upload_tileset_validation_username():