diff --git a/setup.py b/setup.py
index 39046c36..19f50ea5 100644
--- a/setup.py
+++ b/setup.py
@@ -23,7 +23,7 @@ install_requires = [
     "click>=5,<6",
     "colorama",
     "lockfile>=0.9.1,<0.13",
-    "pyserial>=3,<4",
+    "pyserial>=3,<4,!=3.3",
     "requests>=2.4.0,<3",
     "semantic_version>=2.5.0"
 ]