diff --git a/requirements.txt b/requirements.txt
index 1d179dda8..9e207b3bc 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-pyserial (>= 3.0)
+pyserial (>= 3.5)
 pillow ; sys_platform == 'win32'
 wxPython >= 4.2.0
 numpy (>= 1.8.2)