diff --git a/lib/bb/cooker.py b/lib/bb/cooker.py
index 89f1fad0..b041d2a0 100644
--- a/lib/bb/cooker.py
+++ b/lib/bb/cooker.py
@@ -388,12 +388,22 @@ class BBCooker:
             # Create a new hash server bound to a unix domain socket
             if not self.hashserv:
                 dbfile = (self.data.getVar("PERSISTENT_DIR") or self.data.getVar("CACHE")) + "/hashserv.db"
+                upstream = self.data.getVar("BB_HASHSERVE_UPSTREAM") or None
+                if upstream:
+                    import socket
+                    try:
+                        sock = socket.create_connection(upstream.split(":"), 5)
+                        sock.close()
+                    except socket.error as e:
+                        bb.warn("BB_HASHSERVE_UPSTREAM is not valid, unable to connect hash equivalence server at '%s': %s" 
+                                 % (upstream, repr(e)))
+
                 self.hashservaddr = "unix://%s/hashserve.sock" % self.data.getVar("TOPDIR")
                 self.hashserv = hashserv.create_server(
                     self.hashservaddr,
                     dbfile,
                     sync=False,
-                    upstream=self.data.getVar("BB_HASHSERVE_UPSTREAM") or None,
+                    upstream=upstream,
                 )
                 self.hashserv.process = multiprocessing.Process(target=self.hashserv.serve_forever)
                 self.hashserv.process.start()