diff --git a/stomp/test/utils_test.py b/stomp/test/utils_test.py
index 61145a19..7746d89c 100644
--- a/stomp/test/utils_test.py
+++ b/stomp/test/utils_test.py
@@ -29,3 +29,16 @@ def test_parse_headers(self):
         ]
         self.assertEquals(
             {'h1': r'foo:\bar  ', 'h:2': 'baz\r\nquux'}, parse_headers(lines))
+
+    def test_calculate_heartbeats(self):
+        chb = (3000, 5000)
+        shb = map(str, reversed(chb))
+        self.assertEquals((3000, 5000), calculate_heartbeats(shb, chb))
+        shb = ('6000', '2000')
+        self.assertEquals((3000, 6000), calculate_heartbeats(shb, chb))
+        shb = ('0', '0')
+        self.assertEquals((0, 0), calculate_heartbeats(shb, chb))
+        shb = ('10000', '0')
+        self.assertEquals((0, 10000), calculate_heartbeats(shb, chb))
+        chb = (0, 0)
+        self.assertEquals((0, 0), calculate_heartbeats(shb, chb))
diff --git a/stomp/utils.py b/stomp/utils.py
index c205907f..75e12291 100755
--- a/stomp/utils.py
+++ b/stomp/utils.py
@@ -157,9 +157,9 @@ def calculate_heartbeats(shb, chb):
     x = 0
     y = 0
     if cx != 0 and sy != '0':
-        x = max(cx, int(sx))
+        x = max(cx, int(sy))
     if cy != 0 and sx != '0':
-        y = max(cy, int(sy))
+        y = max(cy, int(sx))
     return (x, y)