diff --git a/seahub/api2/endpoints/account.py b/seahub/api2/endpoints/account.py
index c89a0f3f6f..6301594c1e 100644
--- a/seahub/api2/endpoints/account.py
+++ b/seahub/api2/endpoints/account.py
@@ -196,7 +196,7 @@ class Account(APIView):
                 space_quota_mb = int(space_quota_mb)
             except ValueError:
                 return api_error(status.HTTP_400_BAD_REQUEST,
-                        'storage invalid.')
+                        _('Must be an integer that greater than or equal to 0.'))
 
             if space_quota_mb < 0:
                 return api_error(status.HTTP_400_BAD_REQUEST,
diff --git a/seahub/institutions/templates/institutions/user_info.html b/seahub/institutions/templates/institutions/user_info.html
index 0cf612c525..b5a234633f 100644
--- a/seahub/institutions/templates/institutions/user_info.html
+++ b/seahub/institutions/templates/institutions/user_info.html
@@ -52,7 +52,10 @@
             <h3>{% trans "Set user storage limit" %}</h3>
             <input type="hidden" name="email" value="{{ email }}" />
             <input type="text" name="space_quota" /> MB
-            <p class="tip">{% trans "Tip: 0 means default limit" %}</p>
+            <p class="tip">
+            <span>{% trans "An integer that greater than or equal to 0." %}</span><br />
+            <span>{% trans "Tip: 0 means default limit" %}</span>
+            </p>
             <p class="error hide"></p>
             <input type="submit" value="{% trans "Submit" %}" class="submit" />
         </form>
diff --git a/seahub/templates/sysadmin/sys_org_info_base.html b/seahub/templates/sysadmin/sys_org_info_base.html
index dd5afab394..760f001aeb 100644
--- a/seahub/templates/sysadmin/sys_org_info_base.html
+++ b/seahub/templates/sysadmin/sys_org_info_base.html
@@ -31,7 +31,10 @@
     <h3>{% trans "Set org storage limit" %}</h3>
     <input type="hidden" name="org_id" value="{{ org.org_id }}" />
     <input type="text" name="quota" /> MB
-    <p class="tip">{% trans "Tip: 0 means default limit" %}</p>
+    <p class="tip">
+    <span>{% trans "An integer that greater than or equal to 0." %}</span><br />
+    <span>{% trans "Tip: 0 means default limit" %}</span>
+    </p>
     <p class="error hide"></p>
     <input type="submit" value="{% trans "Submit" %}" class="submit" />
 </form>
diff --git a/seahub/templates/sysadmin/sys_user_admin_ldap_imported.html b/seahub/templates/sysadmin/sys_user_admin_ldap_imported.html
index f0ac52ab0e..9ee33c00a0 100644
--- a/seahub/templates/sysadmin/sys_user_admin_ldap_imported.html
+++ b/seahub/templates/sysadmin/sys_user_admin_ldap_imported.html
@@ -78,7 +78,10 @@
 <form id="set-quota-form" method="post" action="" class="hide">{% csrf_token %}
     <h3>{% trans "Set user storage limit" %}</h3>
     <input type="text" name="space_quota" /> MB
-    <p class="tip">{% trans "Tip: 0 means default limit" %}</p>
+    <p class="tip">
+    <span>{% trans "An integer that greater than or equal to 0." %}</span><br />
+    <span>{% trans "Tip: 0 means default limit" %}</span>
+    </p>
     <p class="error hide"></p>
     <input type="submit" value="{% trans "Submit" %}" class="submit" />
 </form>
diff --git a/seahub/templates/sysadmin/useradmin_table.html b/seahub/templates/sysadmin/useradmin_table.html
index 4342d1ccf5..4474a51172 100644
--- a/seahub/templates/sysadmin/useradmin_table.html
+++ b/seahub/templates/sysadmin/useradmin_table.html
@@ -109,7 +109,10 @@
 <form id="set-quota-form" method="post" action="" class="hide">{% csrf_token %}
     <h3>{% trans "Set user storage limit" %}</h3>
     <input type="text" name="space_quota" /> MB
-    <p class="tip">{% trans "Tip: 0 means default limit" %}</p>
+    <p class="tip">
+    <span>{% trans "An integer that greater than or equal to 0." %}</span><br />
+    <span>{% trans "Tip: 0 means default limit" %}</span>
+    </p>
     <p class="error hide"></p>
     <input type="submit" value="{% trans "Submit" %}" class="submit" />
 </form>
diff --git a/seahub/templates/sysadmin/userinfo.html b/seahub/templates/sysadmin/userinfo.html
index 5d9f5fe63b..80d0d3e25d 100644
--- a/seahub/templates/sysadmin/userinfo.html
+++ b/seahub/templates/sysadmin/userinfo.html
@@ -101,7 +101,10 @@
         <form id="set-quota-form" method="post" class="hide">{% csrf_token %}
             <h3>{% trans "Set user storage limit" %}</h3>
             <input type="text" name="space_quota" /> MB
-            <p class="tip">{% trans "Tip: 0 means default limit" %}</p>
+            <p class="tip">
+            <span>{% trans "An integer that greater than or equal to 0." %}</span><br />
+            <span>{% trans "Tip: 0 means default limit" %}</span>
+            </p>
             <p class="error hide"></p>
             <input type="submit" value="{% trans "Submit" %}" class="submit" />
         </form>