diff --git a/esphome/components/modem/sensor/__init__.py b/esphome/components/modem/sensor/__init__.py
index 84df43ae0b..c094e92373 100644
--- a/esphome/components/modem/sensor/__init__.py
+++ b/esphome/components/modem/sensor/__init__.py
@@ -148,7 +148,7 @@ async def to_code(config):
 
     if speed := config.get(CONF_SPEED, None):
         speed_sensor = await sensor.new_sensor(speed)
-        cg.add(var.set_altitude_sensor(speed_sensor))
+        cg.add(var.set_speed_sensor(speed_sensor))
 
     if course := config.get(CONF_COURSE, None):
         course_sensor = await sensor.new_sensor(course)