diff --git a/ChangeLog b/ChangeLog
index 2968cfd..33d8576 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2016.x.x, Version 2.x.x (BETA)
+
+    - Check for correct types using assert in query method.
+
 2016.10.26, Version 2.0.3 (BETA)
 
     - Replaced logging failed ping to prevent unhandled error msg. (issue #2)
diff --git a/siridb/twisted/lib/client.py b/siridb/twisted/lib/client.py
index a03c8d8..6df787a 100644
--- a/siridb/twisted/lib/client.py
+++ b/siridb/twisted/lib/client.py
@@ -162,6 +162,12 @@ def query(self, query, timePrecision=None, timeout=60):
 
         see module doc-string for info on exception handling.
         '''
+        assert isinstance(query, (str, unicode, bytes)), \
+            'query should be of type str, unicode or bytes'
+
+        assert timePrecision is None or isinstance(timePrecision, int), \
+            'timePrecision should be None or an int type.'
+
         tryUnavailable = True
         while True:
             factory = self._getRandomConnection(tryUnavailable)