diff --git a/django/core/db/backends/postgresql.py b/django/core/db/backends/postgresql.py
index 44cb0da2561..b70f286d9d9 100644
--- a/django/core/db/backends/postgresql.py
+++ b/django/core/db/backends/postgresql.py
@@ -18,8 +18,12 @@ class DatabaseWrapper:
         from django.conf.settings import DATABASE_USER, DATABASE_NAME, DATABASE_HOST, DATABASE_PASSWORD, DEBUG, TIME_ZONE
         if self.connection is None:
             # Note that "host=" has to be last, because it might be blank.
-            self.connection = Database.connect("user=%s dbname=%s password=%s host=%s" % \
-                (DATABASE_USER, DATABASE_NAME, DATABASE_PASSWORD, DATABASE_HOST))
+            conn_string = "user=%s dbname=%s" % (DATABASE_USER, DATABASE_NAME)
+            if DATABASE_PASSWORD:
+                conn_string += " password=%s" % DATABASE_PASSWORD
+            if DATABASE_HOST:
+                conn_string += " host=%s" % DATABASE_HOST
+            self.connection = Database.connect(conn_string)
             self.connection.set_isolation_level(1) # make transactions transparent to all cursors
         cursor = self.connection.cursor()
         cursor.execute("SET TIME ZONE %s", [TIME_ZONE])