diff --git a/mitmproxy/net/http/url.py b/mitmproxy/net/http/url.py
index 86f65cfdc..f938cb12d 100644
--- a/mitmproxy/net/http/url.py
+++ b/mitmproxy/net/http/url.py
@@ -76,7 +76,7 @@ def encode(s: Sequence[Tuple[str, str]], similar_to: str=None) -> str:
 
     encoded = urllib.parse.urlencode(s, False, errors="surrogateescape")
 
-    if remove_trailing_equal:
+    if encoded and remove_trailing_equal:
         encoded = encoded.replace("=&", "&")
         if encoded[-1] == '=':
             encoded = encoded[:-1]
diff --git a/test/mitmproxy/net/http/test_url.py b/test/mitmproxy/net/http/test_url.py
index 2064aab8d..c9f61fafd 100644
--- a/test/mitmproxy/net/http/test_url.py
+++ b/test/mitmproxy/net/http/test_url.py
@@ -108,6 +108,7 @@ def test_empty_key_trailing_equal_sign():
 def test_encode():
     assert url.encode([('foo', 'bar')])
     assert url.encode([('foo', surrogates)])
+    assert not url.encode([], similar_to="justatext")
 
 
 def test_decode():