diff --git a/lib/connect.js b/lib/connect.js
index 603f1981..187a6d99 100644
--- a/lib/connect.js
+++ b/lib/connect.js
@@ -67,7 +67,7 @@ function openFrames(vhost, query, credentials, extraClientProperties) {
     // tune-ok
     'channelMax': intOrDefault(query.channelMax, 0),
     'frameMax': intOrDefault(query.frameMax, 0x1000),
-    'heartbeat': intOrDefault(query.heartbeat, 0),
+    'heartbeat': intOrDefault(query.heartbeat, null),
 
     // open
     'virtualHost': vhost,
diff --git a/lib/connection.js b/lib/connection.js
index f65138c5..23667765 100644
--- a/lib/connection.js
+++ b/lib/connection.js
@@ -189,7 +189,7 @@ C.open = function(allFields, openCallback0) {
     // frameMax, but we'll leave that to the server to enforce). In
     // all cases, `0` really means "no limit", or rather the highest
     // value in the encoding, e.g., unsigned short for channelMax.
-    if (server === 0 || desired === 0) {
+    if (server === 0 || desired === 0 || desired === null) {
       // i.e., whichever places a limit, if either
       return Math.max(server, desired);
     }
@@ -227,7 +227,7 @@ C.open = function(allFields, openCallback0) {
       tunedOptions.channelMax =
         negotiate(fields.channelMax, allFields.channelMax);
       tunedOptions.heartbeat =
-        negotiate(fields.heartbeat, allFields.heartbeat);
+        allFields.heartbeat === null ? fields.heartbeat : allFields.heartbeat
       send(defs.ConnectionTuneOk);
       send(defs.ConnectionOpen);
       expect(defs.ConnectionOpenOk, onOpenOk);