diff --git a/django_q/conf.py b/django_q/conf.py
index ccf8a5d..dfa719a 100644
--- a/django_q/conf.py
+++ b/django_q/conf.py
@@ -73,6 +73,8 @@ class Conf(object):
 
     # Guard loop sleep in seconds
     GUARD_CYCLE = conf.get('guard_cycle', 0.5)
+    if GUARD_CYCLE <= 0 or GUARD_CYCLE >= 60:
+        raise ValueError('`guard_cycle` must be greater than 0 and less than 60 sec')
 
     # Disable the scheduler
     SCHEDULER = conf.get('scheduler', True)
diff --git a/docs/configure.rst b/docs/configure.rst
index 73a1c6a..714881a 100644
--- a/docs/configure.rst
+++ b/docs/configure.rst
@@ -81,7 +81,7 @@ Limits the amount of successful tasks saved to Django.
 guard_cycle
 ~~~~~~~~~~~
 
-Guard loop sleep in seconds
+Guard loop sleep in seconds, must be greater than 0 and less than 60.
 
 .. _sync: