diff --git a/esphomeyaml/components/binary_sensor/template.py b/esphomeyaml/components/binary_sensor/template.py
index 663e82430f..29e5e7a8ad 100644
--- a/esphomeyaml/components/binary_sensor/template.py
+++ b/esphomeyaml/components/binary_sensor/template.py
@@ -3,7 +3,7 @@ import voluptuous as vol
 import esphomeyaml.config_validation as cv
 from esphomeyaml.components import binary_sensor
 from esphomeyaml.const import CONF_LAMBDA, CONF_MAKE_ID, CONF_NAME
-from esphomeyaml.helpers import App, Application, process_lambda, variable
+from esphomeyaml.helpers import App, Application, process_lambda, variable, optional, bool_
 
 MakeTemplateBinarySensor = Application.MakeTemplateBinarySensor
 
@@ -15,7 +15,8 @@ PLATFORM_SCHEMA = binary_sensor.PLATFORM_SCHEMA.extend({
 
 def to_code(config):
     template_ = None
-    for template_ in process_lambda(config[CONF_LAMBDA], []):
+    for template_ in process_lambda(config[CONF_LAMBDA], [],
+                                    return_type=optional.template(bool_)):
         yield
     rhs = App.make_template_binary_sensor(config[CONF_NAME], template_)
     make = variable(config[CONF_MAKE_ID], rhs)
diff --git a/esphomeyaml/components/cover/template.py b/esphomeyaml/components/cover/template.py
index 4e85bded86..f771f89074 100644
--- a/esphomeyaml/components/cover/template.py
+++ b/esphomeyaml/components/cover/template.py
@@ -5,7 +5,7 @@ from esphomeyaml import automation
 from esphomeyaml.components import cover
 from esphomeyaml.const import CONF_CLOSE_ACTION, CONF_LAMBDA, CONF_MAKE_ID, CONF_NAME, \
     CONF_OPEN_ACTION, CONF_STOP_ACTION, CONF_OPTIMISTIC
-from esphomeyaml.helpers import App, Application, NoArg, add, process_lambda, variable
+from esphomeyaml.helpers import App, Application, NoArg, add, process_lambda, variable, optional
 
 MakeTemplateCover = Application.MakeTemplateCover
 
@@ -25,7 +25,8 @@ def to_code(config):
 
     if CONF_LAMBDA in config:
         template_ = None
-        for template_ in process_lambda(config[CONF_LAMBDA], []):
+        for template_ in process_lambda(config[CONF_LAMBDA], [],
+                                        return_type=optional.template(cover.CoverState)):
             yield
         add(make.Ptemplate_.set_state_lambda(template_))
     if CONF_OPEN_ACTION in config:
diff --git a/esphomeyaml/components/output/ledc.py b/esphomeyaml/components/output/ledc.py
index 60488e364c..107e788737 100644
--- a/esphomeyaml/components/output/ledc.py
+++ b/esphomeyaml/components/output/ledc.py
@@ -15,7 +15,7 @@ def validate_frequency_bit_depth(obj):
     bit_depth = obj.get(CONF_BIT_DEPTH, 12)
     max_freq = APB_CLOCK_FREQ / (2**bit_depth)
     if frequency > max_freq:
-        raise vol.Invalid('Maximum frequency for bit depth {} is {}'.format(bit_depth, max_freq))
+        raise vol.Invalid('Maximum frequency for bit depth {} is {}Hz'.format(bit_depth, max_freq))
     return obj
 
 
diff --git a/esphomeyaml/components/sensor/template.py b/esphomeyaml/components/sensor/template.py
index 78ae6b7021..6b2ced2d5b 100644
--- a/esphomeyaml/components/sensor/template.py
+++ b/esphomeyaml/components/sensor/template.py
@@ -3,7 +3,7 @@ import voluptuous as vol
 import esphomeyaml.config_validation as cv
 from esphomeyaml.components import sensor
 from esphomeyaml.const import CONF_LAMBDA, CONF_MAKE_ID, CONF_NAME, CONF_UPDATE_INTERVAL
-from esphomeyaml.helpers import App, process_lambda, variable, Application
+from esphomeyaml.helpers import App, process_lambda, variable, Application, float_, optional
 
 MakeTemplateSensor = Application.MakeTemplateSensor
 
@@ -16,7 +16,8 @@ PLATFORM_SCHEMA = sensor.PLATFORM_SCHEMA.extend({
 
 def to_code(config):
     template_ = None
-    for template_ in process_lambda(config[CONF_LAMBDA], []):
+    for template_ in process_lambda(config[CONF_LAMBDA], [],
+                                    return_type=optional.template(float_)):
         yield
     rhs = App.make_template_sensor(config[CONF_NAME], template_,
                                    config.get(CONF_UPDATE_INTERVAL))
diff --git a/esphomeyaml/components/switch/template.py b/esphomeyaml/components/switch/template.py
index 1aed25db0a..cbad5833c6 100644
--- a/esphomeyaml/components/switch/template.py
+++ b/esphomeyaml/components/switch/template.py
@@ -5,7 +5,8 @@ from esphomeyaml import automation
 from esphomeyaml.components import switch
 from esphomeyaml.const import CONF_LAMBDA, CONF_MAKE_ID, CONF_NAME, CONF_TURN_OFF_ACTION, \
     CONF_TURN_ON_ACTION, CONF_OPTIMISTIC
-from esphomeyaml.helpers import App, Application, process_lambda, variable, NoArg, add
+from esphomeyaml.helpers import App, Application, process_lambda, variable, NoArg, add, bool_, \
+    optional
 
 MakeTemplateSwitch = Application.MakeTemplateSwitch
 
@@ -24,7 +25,8 @@ def to_code(config):
 
     if CONF_LAMBDA in config:
         template_ = None
-        for template_ in process_lambda(config[CONF_LAMBDA], []):
+        for template_ in process_lambda(config[CONF_LAMBDA], [],
+                                        return_type=optional.template(bool_)):
             yield
         add(make.Ptemplate_.set_state_lambda(template_))
     if CONF_TURN_OFF_ACTION in config: