diff --git a/docs/topic/tljh-config.rst b/docs/topic/tljh-config.rst
index 0570d63..4c62e17 100644
--- a/docs/topic/tljh-config.rst
+++ b/docs/topic/tljh-config.rst
@@ -81,7 +81,8 @@ User Server Limits
 
 
 * ``limits.memory`` Specifies the maximum memory that can be used by each
-  individual user. It can be specified as an absolute byte value. You can use
+  individual user. By default there is no memory limit. The limit can be
+  specified as an absolute byte value. You can use
   the suffixes K, M, G or T to mean Kilobyte, Megabyte, Gigabyte or Terabyte
   respectively. Setting it to ``None`` disables memory limits.
 
@@ -95,6 +96,7 @@ User Server Limits
   handedly take down the machine accidentally by OOMing it.
 
 * ``limits.cpu`` A float representing the total CPU-cores each user can use.
+  By default there is no CPU limit.
   1 represents one full CPU, 4 represents 4 full CPUs, 0.5 represents
   half of one CPU, etc. This value is ultimately converted to a percentage and
   rounded down to the nearest integer percentage,
diff --git a/tests/test_configurer.py b/tests/test_configurer.py
index df4b69f..59dd6ec 100644
--- a/tests/test_configurer.py
+++ b/tests/test_configurer.py
@@ -59,6 +59,22 @@ def apply_mock_config(overrides):
     return c
 
 
+def test_default_memory_limit():
+    """
+    Test default per user memory limit
+    """
+    c = apply_mock_config({})
+    assert c.SystemdSpawner.mem_limit is None
+
+
+def test_set_memory_limit():
+    """
+    Test setting per user memory limit
+    """
+    c = apply_mock_config({'limits': {'memory': '42G'}})
+    assert c.SystemdSpawner.mem_limit == '42G'
+
+
 def test_app_default():
     """
     Test default application with no config overrides.
diff --git a/tljh/configurer.py b/tljh/configurer.py
index 29eb49f..0cc4694 100644
--- a/tljh/configurer.py
+++ b/tljh/configurer.py
@@ -28,7 +28,7 @@ default = {
         'admin': [],
     },
     'limits': {
-        'memory': '1G',
+        'memory': None,
         'cpu': None,
     },
     'http': {