diff --git a/homeassistant/components/modbus/manifest.json b/homeassistant/components/modbus/manifest.json
index 6b072457144..14faad789fe 100644
--- a/homeassistant/components/modbus/manifest.json
+++ b/homeassistant/components/modbus/manifest.json
@@ -6,5 +6,5 @@
   "iot_class": "local_polling",
   "loggers": ["pymodbus"],
   "quality_scale": "gold",
-  "requirements": ["pymodbus==3.6.5"]
+  "requirements": ["pymodbus==3.6.6"]
 }
diff --git a/requirements_all.txt b/requirements_all.txt
index f11d17fc8cb..c147e265ec2 100644
--- a/requirements_all.txt
+++ b/requirements_all.txt
@@ -1971,7 +1971,7 @@ pymitv==1.4.3
 pymochad==0.2.0
 
 # homeassistant.components.modbus
-pymodbus==3.6.5
+pymodbus==3.6.6
 
 # homeassistant.components.monoprice
 pymonoprice==0.4
diff --git a/requirements_test_all.txt b/requirements_test_all.txt
index d11bba443cc..7636d8c6b18 100644
--- a/requirements_test_all.txt
+++ b/requirements_test_all.txt
@@ -1525,7 +1525,7 @@ pymeteoclimatic==0.1.0
 pymochad==0.2.0
 
 # homeassistant.components.modbus
-pymodbus==3.6.5
+pymodbus==3.6.6
 
 # homeassistant.components.monoprice
 pymonoprice==0.4