diff --git a/moto/iot/exceptions.py b/moto/iot/exceptions.py
index 0e1ac8937..4bb01c095 100644
--- a/moto/iot/exceptions.py
+++ b/moto/iot/exceptions.py
@@ -1,14 +1,14 @@
 from __future__ import unicode_literals
-from moto.core.exceptions import RESTError
+from moto.core.exceptions import JsonRESTError
 
 
-class IoTClientError(RESTError):
+class IoTClientError(JsonRESTError):
     code = 400
 
 
 class ResourceNotFoundException(IoTClientError):
     def __init__(self):
-        self.code = 400
+        self.code = 404
         super(ResourceNotFoundException, self).__init__(
             "ResourceNotFoundException",
             "The specified resource does not exist"
diff --git a/moto/iotdata/exceptions.py b/moto/iotdata/exceptions.py
index d55b16e3c..ddc6b37fd 100644
--- a/moto/iotdata/exceptions.py
+++ b/moto/iotdata/exceptions.py
@@ -1,14 +1,14 @@
 from __future__ import unicode_literals
-from moto.core.exceptions import RESTError
+from moto.core.exceptions import JsonRESTError
 
 
-class IoTDataPlaneClientError(RESTError):
+class IoTDataPlaneClientError(JsonRESTError):
     code = 400
 
 
 class ResourceNotFoundException(IoTDataPlaneClientError):
     def __init__(self):
-        self.code = 400
+        self.code = 404
         super(ResourceNotFoundException, self).__init__(
             "ResourceNotFoundException",
             "The specified resource does not exist"