diff --git a/earwigbot/wiki/category.py b/earwigbot/wiki/category.py
index 9f43e7b..e0209b2 100644
--- a/earwigbot/wiki/category.py
+++ b/earwigbot/wiki/category.py
@@ -55,7 +55,7 @@ class Category(Page):
         title = self.title().replace(" ", "_").split(":", 1)[1]
 
         if limit:
-            query += " LIMIT = ?"
+            query += " LIMIT ?"
             result = self._site.sql_query(query, (title, limit))
         else:
             result = self._site.sql_query(query, (title,))
diff --git a/earwigbot/wiki/page.py b/earwigbot/wiki/page.py
index 957878e..701500e 100644
--- a/earwigbot/wiki/page.py
+++ b/earwigbot/wiki/page.py
@@ -194,19 +194,17 @@ class Page(CopyrightMixin):
         else:
             self._is_redirect = True
 
-        self._pageid = result["query"]["pages"].keys()[0]
-        if int(self._pageid) < 0:
-            try:
-                res["missing"]
-            except KeyError:
+        self._pageid = int(result["query"]["pages"].keys()[0])
+        if self._pageid < 0:
+            if "missing" in res:
+                # If it has a negative ID and it's missing; we can still get
+                # data like the namespace, protection, and URL:
+                self._exists = 2
+            else:
                 # If it has a negative ID and it's invalid, then break here,
                 # because there's no other data for us to get:
                 self._exists = 1
                 return
-            else:
-                # If it has a negative ID and it's missing; we can still get
-                # data like the namespace, protection, and URL:
-                self._exists = 2
         else:
             self._exists = 3
 
diff --git a/earwigbot/wiki/site.py b/earwigbot/wiki/site.py
index d723bdb..2675ed0 100644
--- a/earwigbot/wiki/site.py
+++ b/earwigbot/wiki/site.py
@@ -27,6 +27,7 @@ from logging import getLogger, NullHandler
 from os.path import expanduser
 from re import escape as re_escape, match as re_match
 from StringIO import StringIO
+from threading import Lock
 from time import sleep, time
 from urllib import unquote_plus, urlencode
 from urllib2 import build_opener, HTTPCookieProcessor, URLError
@@ -114,6 +115,7 @@ class Site(object):
         # Attributes used for SQL queries:
         self._sql_data = sql
         self._sql_conn = None
+        self._sql_lock = Lock()
 
         # Attribute used in copyright violation checks (see CopyrightMixin):
         self._search_config = search_config
@@ -577,19 +579,20 @@ class Site(object):
         (oursql.ProgrammingError, oursql.InterfaceError, ...) if there were
         problems with the query.
         """
-        if not self._sql_conn:
-            self._sql_connect()
-
         if not cursor_class:
             if dict_cursor:
                 cursor_class = oursql.DictCursor
             else:
                 cursor_class = oursql.Cursor
-
-        with self._sql_conn.cursor(cursor_class, show_table=show_table) as cur:
-            cur.execute(query, params, plain_query)
-            for result in cur:
-                yield result
+        klass = cursor_class
+
+        with self._sql_lock:
+            if not self._sql_conn:
+                self._sql_connect()
+            with self._sql_conn.cursor(klass, show_table=show_table) as cur:
+                cur.execute(query, params, plain_query)
+                for result in cur:
+                    yield result
 
     def get_replag(self):
         """Return the estimated database replication lag in seconds.