diff --git a/toolkit/components/places/src/nsNavHistory.cpp b/toolkit/components/places/src/nsNavHistory.cpp
index 66d2a027f400..901b7c31c8f6 100644
--- a/toolkit/components/places/src/nsNavHistory.cpp
+++ b/toolkit/components/places/src/nsNavHistory.cpp
@@ -794,6 +794,12 @@ nsNavHistory::InitDB(PRInt16 *aMadeChanges)
   rv = mDBConn->ExecuteSimpleSQL(cacheSizePragma);
   NS_ENSURE_SUCCESS(rv, rv);
 
+  // lock the db file
+  // http://www.sqlite.org/pragma.html#pragma_locking_mode
+  rv = mDBConn->ExecuteSimpleSQL(
+    NS_LITERAL_CSTRING("PRAGMA locking_mode = EXCLUSIVE"));
+  NS_ENSURE_SUCCESS(rv, rv);
+
   // moz_places
   if (!tableExists) {
     *aMadeChanges = DB_MIGRATION_CREATED;