diff --git a/homeassistant/components/modbus/__init__.py b/homeassistant/components/modbus/__init__.py
index 182e3dc28fa..0500a904cb9 100644
--- a/homeassistant/components/modbus/__init__.py
+++ b/homeassistant/components/modbus/__init__.py
@@ -60,7 +60,9 @@ SERVICE_WRITE_REGISTER_SCHEMA = vol.Schema({
     vol.Optional(ATTR_HUB, default=DEFAULT_HUB): cv.string,
     vol.Required(ATTR_UNIT): cv.positive_int,
     vol.Required(ATTR_ADDRESS): cv.positive_int,
-    vol.Required(ATTR_VALUE): vol.All(cv.ensure_list, [cv.positive_int])
+    vol.Required(ATTR_VALUE): vol.Any(
+        cv.positive_int,
+        vol.All(cv.ensure_list, [cv.positive_int]))
 })
 
 SERVICE_WRITE_COIL_SCHEMA = vol.Schema({
diff --git a/homeassistant/components/modbus/services.yaml b/homeassistant/components/modbus/services.yaml
index 0fd9e5a49e7..48e9e815aaa 100644
--- a/homeassistant/components/modbus/services.yaml
+++ b/homeassistant/components/modbus/services.yaml
@@ -9,4 +9,4 @@ write_register:
   fields:
     address: {description: Address of the holding register to write to., example: 0}
     unit: {description: Address of the modbus unit., example: 21}
-    value: {description: Value to write., example: 0}
+    value: {description: Value (single value or array) to write., example: 0 or [4,0]}