diff --git a/include/modules/river/tags.hpp b/include/modules/river/tags.hpp
index f80b3c59..9b75fbd3 100644
--- a/include/modules/river/tags.hpp
+++ b/include/modules/river/tags.hpp
@@ -18,6 +18,7 @@ class Tags : public waybar::AModule {
   // Handlers for wayland events
   void handle_focused_tags(uint32_t tags);
   void handle_view_tags(struct wl_array *tags);
+  void handle_urgent_tags(uint32_t tags);
 
   struct zriver_status_manager_v1 *status_manager_;
 
diff --git a/man/waybar-river-tags.5.scd b/man/waybar-river-tags.5.scd
index 0f027249..65b90332 100644
--- a/man/waybar-river-tags.5.scd
+++ b/man/waybar-river-tags.5.scd
@@ -15,7 +15,7 @@ Addressed by *river/tags*
 *num-tags*: ++
     typeof: uint ++
     default: 9 ++
-    The number of tags that should be displayed.
+    The number of tags that should be displayed. Max 32.
 
 *tag-labels*: ++
     typeof: array ++
@@ -34,8 +34,10 @@ Addressed by *river/tags*
 - *#tags button*
 - *#tags button.occupied*
 - *#tags button.focused*
+- *#tags button.urgent*
 
-Note that a tag can be both occupied and focused at the same time.
+Note that occupied/focused/urgent status may overlap. That is, a tag may be
+both occupied and focused at the same time.
 
 # SEE ALSO
 
diff --git a/protocol/river-status-unstable-v1.xml b/protocol/river-status-unstable-v1.xml
index a4d6f4e5..13affaa7 100644
--- a/protocol/river-status-unstable-v1.xml
+++ b/protocol/river-status-unstable-v1.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <protocol name="river_status_unstable_v1">
   <copyright>
-    Copyright 2020 Isaac Freund
+    Copyright 2020 The River Developers
 
     Permission to use, copy, modify, and/or distribute this software for any
     purpose with or without fee is hereby granted, provided that the above
@@ -16,7 +16,7 @@
     OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   </copyright>
 
-  <interface name="zriver_status_manager_v1" version="1">
+  <interface name="zriver_status_manager_v1" version="2">
     <description summary="manage river status objects">
       A global factory for objects that receive status information specific
       to river. It could be used to implement, for example, a status bar.
@@ -47,7 +47,7 @@
     </request>
   </interface>
 
-  <interface name="zriver_output_status_v1" version="1">
+  <interface name="zriver_output_status_v1" version="2">
     <description summary="track output tags and focus">
       This interface allows clients to receive information about the current
       windowing state of an output.
@@ -75,12 +75,21 @@
       </description>
       <arg name="tags" type="array" summary="array of 32-bit bitfields"/>
     </event>
+
+    <event name="urgent_tags" since="2">
+      <description summary="tags of the output with an urgent view">
+        Sent once on binding the interface and again whenever the set of
+        tags with at least one urgent view changes.
+      </description>
+      <arg name="tags" type="uint" summary="32-bit bitfield"/>
+    </event>
   </interface>
 
   <interface name="zriver_seat_status_v1" version="1">
     <description summary="track seat focus">
       This interface allows clients to receive information about the current
-      focus of a seat.
+      focus of a seat. Note that (un)focused_output events will only be sent
+      if the client has bound the relevant wl_output globals.
     </description>
 
     <request name="destroy" type="destructor">
diff --git a/src/modules/river/tags.cpp b/src/modules/river/tags.cpp
index e96b2016..2628af2d 100644
--- a/src/modules/river/tags.cpp
+++ b/src/modules/river/tags.cpp
@@ -22,14 +22,24 @@ static void listen_view_tags(void *data, struct zriver_output_status_v1 *zriver_
   static_cast<Tags *>(data)->handle_view_tags(tags);
 }
 
+static void listen_urgent_tags(void *data, struct zriver_output_status_v1 *zriver_output_status_v1,
+                               uint32_t tags) {
+  static_cast<Tags *>(data)->handle_urgent_tags(tags);
+}
+
 static const zriver_output_status_v1_listener output_status_listener_impl{
     .focused_tags = listen_focused_tags,
     .view_tags = listen_view_tags,
+    .urgent_tags = listen_urgent_tags,
 };
 
 static void handle_global(void *data, struct wl_registry *registry, uint32_t name,
                           const char *interface, uint32_t version) {
   if (std::strcmp(interface, zriver_status_manager_v1_interface.name) == 0) {
+    version = std::min<uint32_t>(version, 2);
+    if (version < ZRIVER_OUTPUT_STATUS_V1_URGENT_TAGS_SINCE_VERSION) {
+      spdlog::warn("river server does not support urgent tags");
+    }
     static_cast<Tags *>(data)->status_manager_ = static_cast<struct zriver_status_manager_v1 *>(
         wl_registry_bind(registry, name, &zriver_status_manager_v1_interface, version));
   }
@@ -64,8 +74,9 @@ Tags::Tags(const std::string &id, const waybar::Bar &bar, const Json::Value &con
   }
   event_box_.add(box_);
 
-  // Default to 9 tags
-  const uint32_t num_tags = config["num-tags"].isUInt() ? config_["num-tags"].asUInt() : 9;
+  // Default to 9 tags, cap at 32
+  const uint32_t num_tags =
+      config["num-tags"].isUInt() ? std::min<uint32_t>(32, config_["num-tags"].asUInt()) : 9;
 
   std::vector<std::string> tag_labels(num_tags);
   for (uint32_t tag = 0; tag < num_tags; ++tag) {
@@ -129,4 +140,16 @@ void Tags::handle_view_tags(struct wl_array *view_tags) {
   }
 }
 
+void Tags::handle_urgent_tags(uint32_t tags) {
+  uint32_t i = 0;
+  for (auto &button : buttons_) {
+    if ((1 << i) & tags) {
+      button.get_style_context()->add_class("urgent");
+    } else {
+      button.get_style_context()->remove_class("urgent");
+    }
+    ++i;
+  }
+}
+
 } /* namespace waybar::modules::river */