diff --git a/asks/request_object.py b/asks/request_object.py
index 2f4a7ae..2a2a80e 100644
--- a/asks/request_object.py
+++ b/asks/request_object.py
@@ -440,14 +440,17 @@ def _dict_to_query(data, params=True, base_query=False):
                     query.append('='.join(quote_plus(x) for x in (k, key)))
             elif hasattr(v, '__iter__'):
                 for elm in v:
-                    query.append('='.join(quote_plus(x) for x in (k,
-                                 quote_plus('+'.join(str(elm).split())))))
-
+                    if elm is None:
+                        continue
+                    try:
+                        elm_quoted = '+'.join(quote_plus(str(y)) for y in elm.split())
+                    except AttributeError:  # not a string
+                        elm_quoted = str(elm)
+                    query.append('='.join((quote_plus(k), elm_quoted)))
         if params and query:
             if not base_query:
                 return requote_uri('?' + '&'.join(query))
-            else:
-                return requote_uri('&' + '&'.join(query))
+            return requote_uri('&' + '&'.join(query))
 
         return requote_uri('&'.join(query))
 
diff --git a/tests/test_request_object.py b/tests/test_request_object.py
index 9627a99..b5cb85e 100644
--- a/tests/test_request_object.py
+++ b/tests/test_request_object.py
@@ -40,6 +40,9 @@ def test_http1_0(monkeypatch):
     [{'zero': 0}, '?zero=0'],
     [{'empty': ''}, '?empty='],
     [{'false': False}, '?false=False'],
+    [{'foo': 'abc', 'bar': 'jkl'}, '?foo=abc&bar=jkl'],
+    [{'foo': ['abc def', 'ghi'], 'bar baz': 'jkl'}, '?foo=abc+def&foo=ghi&bar+baz=jkl'],
+    [{'foo bar': 5, 'baz': [123, 456], 'qux': ['abc', 789, None]}, '?foo+bar=5&baz=123&baz=456&qux=abc&qux=789']
 ])
 def test_dict_to_query(data, query_str):
     assert RequestProcessor._dict_to_query(data) == query_str