diff --git a/homeassistant/components/binary_sensor/isy994.py b/homeassistant/components/binary_sensor/isy994.py
index 14168907224..89d9b7e5c8f 100644
--- a/homeassistant/components/binary_sensor/isy994.py
+++ b/homeassistant/components/binary_sensor/isy994.py
@@ -55,10 +55,9 @@ def setup_platform(hass, config: ConfigType,
                           node.nid, node.parent_nid)
         else:
             device_type = _detect_device_type(node)
-            if device_type in ['moisture', 'opening']:
-                subnode_id = int(node.nid[-1])
-                # Leak and door/window sensors work the same way with negative
-                # nodes and heartbeat nodes
+            subnode_id = int(node.nid[-1])
+            if device_type == 'opening':
+                # Door/window sensors use an optional "negative" node
                 if subnode_id == 4:
                     # Subnode 4 is the heartbeat node, which we will represent
                     # as a separate binary_sensor
@@ -67,6 +66,14 @@ def setup_platform(hass, config: ConfigType,
                     devices.append(device)
                 elif subnode_id == 2:
                     parent_device.add_negative_node(node)
+            elif device_type == 'moisture':
+                # Moisure nodes have a subnode 2, but we ignore it because it's
+                # just the inverse of the primary node.
+                if subnode_id == 4:
+                    # Heartbeat node
+                    device = ISYBinarySensorHeartbeat(node, parent_device)
+                    parent_device.add_heartbeat_device(device)
+                    devices.append(device)
             else:
                 # We don't yet have any special logic for other sensor types,
                 # so add the nodes as individual devices