diff --git a/gitosis/serve.py b/gitosis/serve.py
index 4b7c6a7..551ac46 100644
--- a/gitosis/serve.py
+++ b/gitosis/serve.py
@@ -54,7 +54,11 @@ def serve(
     if '\n' in command:
         raise CommandMayNotContainNewlineError()
 
-    verb, args = command.split(None, 1)
+    try:
+        verb, args = command.split(None, 1)
+    except ValueError:
+        # all known commands take one argument; improve if/when needed
+        raise UnknownCommandError()
 
     if (verb not in COMMANDS_WRITE
         and verb not in COMMANDS_READONLY):
diff --git a/gitosis/test/test_serve.py b/gitosis/test/test_serve.py
index a79dbaf..416587a 100644
--- a/gitosis/test/test_serve.py
+++ b/gitosis/test/test_serve.py
@@ -21,6 +21,18 @@ def test_bad_newLine():
     eq(str(e), 'Command may not contain newline')
     assert isinstance(e, serve.ServingError)
 
+def test_bad_nospace():
+    cfg = RawConfigParser()
+    e = assert_raises(
+        serve.UnknownCommandError,
+        serve.serve,
+        cfg=cfg,
+        user='jdoe',
+        command='git-upload-pack',
+        )
+    eq(str(e), 'Unknown command denied')
+    assert isinstance(e, serve.ServingError)
+
 def test_bad_command():
     cfg = RawConfigParser()
     e = assert_raises(