diff --git a/homeassistant/package_constraints.txt b/homeassistant/package_constraints.txt
index 21bd4fb2d1b..eb1bfe5ff21 100644
--- a/homeassistant/package_constraints.txt
+++ b/homeassistant/package_constraints.txt
@@ -197,3 +197,7 @@ scapy>=2.5.0
 # Only tuf>=4 includes a constraint to <1.0.
 # https://github.com/theupdateframework/python-tuf/releases/tag/v4.0.0
 tuf>=4.0.0
+
+# pyserial-asyncio does blocking I/O in asyncio loop, use pyserial-asyncio-fast
+# instead as pyserial-asyncio is not maintained
+pyserial-asyncio==1000000000.0.0
diff --git a/script/gen_requirements_all.py b/script/gen_requirements_all.py
index 1f2f4bcab66..d0341aab03e 100755
--- a/script/gen_requirements_all.py
+++ b/script/gen_requirements_all.py
@@ -219,6 +219,10 @@ scapy>=2.5.0
 # Only tuf>=4 includes a constraint to <1.0.
 # https://github.com/theupdateframework/python-tuf/releases/tag/v4.0.0
 tuf>=4.0.0
+
+# pyserial-asyncio does blocking I/O in asyncio loop, use pyserial-asyncio-fast
+# instead as pyserial-asyncio is not maintained
+pyserial-asyncio==1000000000.0.0
 """
 
 GENERATED_MESSAGE = (