diff --git a/protocol/dmx/universe.cpp b/protocol/dmx/universe.cpp
index bd005fc..3e18947 100644
--- a/protocol/dmx/universe.cpp
+++ b/protocol/dmx/universe.cpp
@@ -50,7 +50,7 @@ Universe::~Universe()
  * @param address
  * @return
  */
-uint8_t Universe::slot(const uint16_t address) const
+uint8_t Universe::slot(const uint16_t address)
 {
   if (address == 0)
     return 0;
diff --git a/protocol/dmx/universe.h b/protocol/dmx/universe.h
index 0cc540c..339bf29 100644
--- a/protocol/dmx/universe.h
+++ b/protocol/dmx/universe.h
@@ -50,7 +50,7 @@ class Universe {
     Universe (int timeout_period = E111_DATA_LOSS_TIMEOUT);
     virtual ~Universe ();
 
-    virtual uint8_t slot (const uint16_t) const;
+    virtual uint8_t slot (const uint16_t);
     virtual double rxRate();
     virtual uint rxAge();
 
diff --git a/protocol/sacn/arbitratinguniverse.cpp b/protocol/sacn/arbitratinguniverse.cpp
index 82bad5a..78bcd6e 100644
--- a/protocol/sacn/arbitratinguniverse.cpp
+++ b/protocol/sacn/arbitratinguniverse.cpp
@@ -135,7 +135,7 @@ void ArbitratingUniverse::onSourceListChange(std::function<void()> cb)
  * @brief MergeProxyUniverse::isSyncronized
  * @return
  */
-bool ArbitratingUniverse::isSyncronized() const
+bool ArbitratingUniverse::isSyncronized()
 {
   auto universe = dominant_();
   if (!universe)
@@ -148,7 +148,7 @@ bool ArbitratingUniverse::isSyncronized() const
  * @brief MergeProxyUniverse::provenance
  * @return
  */
-std::shared_ptr<DATA::data_header> ArbitratingUniverse::provenance() const
+std::shared_ptr<DATA::data_header> ArbitratingUniverse::provenance()
 {
   auto universe = dominant_();
   if (universe)
@@ -197,7 +197,7 @@ bool ArbitratingUniverse::isEditable() const {
 }
 
 
-uint16_t ArbitratingUniverse::activeSlots() const
+uint16_t ArbitratingUniverse::activeSlots()
 {
   auto universe = dominant_();
   if (!universe)
@@ -211,7 +211,7 @@ uint16_t ArbitratingUniverse::activeSlots() const
  * @param s
  * @return
  */
-uint8_t ArbitratingUniverse::slot(const uint16_t s) const
+uint8_t ArbitratingUniverse::slot(const uint16_t s)
 {
   auto universe = dominant_();
   if (!universe)
@@ -237,16 +237,47 @@ double ArbitratingUniverse::rxRate()
  * @brief MergeProxyUniverse::dominant_
  * @return
  */
-std::shared_ptr<Universe> ArbitratingUniverse::dominant_() const
+std::shared_ptr<Universe> ArbitratingUniverse::dominant_()
 {
+  bool sourceListChanged = false;
   std::shared_ptr<Universe> ret = nullptr;
-  for (auto& [_, uni] : sources_)
+
+  for(auto it = sources_.begin(); it != sources_.end(); )
     {
-      if (uni->rxRate() < (DMX::E111_DATA_LOSS_TIMEOUT / 1000.0))
-        continue;   // stale universes cannot be dominant
-      if (!ret || uni->provenance() > ret->provenance())
-        ret = uni;
+      auto universe = it->second;
+
+      if (!ret)
+        { // anything is better than nothing!
+          ++it;
+          ret = universe;
+          continue;
+        }
+
+      auto age = universe->rxAge();
+
+      if (age > E131_NETWORK_DATA_LOSS_TIMEOUT)
+        { // clean up zombie universes
+          it = sources_.erase(it);
+          sourceListChanged = true;
+          continue;
+        }
+
+      if (age > DMX::E111_DATA_LOSS_TIMEOUT)
+        {
+          ++it;
+          continue;  // stale universes cannot be dominant
+        }
+
+      if (!ret || universe->provenance() > ret->provenance())
+        ret = universe; // rank by provenance
+
+      ++it;
     }
+
+  if (sourceListChanged)
+    for (const auto & cb : cb_sourceListChange)
+      cb();
+
   return ret;
 }
 
diff --git a/protocol/sacn/arbitratinguniverse.h b/protocol/sacn/arbitratinguniverse.h
index 96fbb5e..97c4d3e 100644
--- a/protocol/sacn/arbitratinguniverse.h
+++ b/protocol/sacn/arbitratinguniverse.h
@@ -68,15 +68,15 @@ public:
     // SACN::Universe overrides:
     void set(std::shared_ptr<ACN::DMP::Pdu>, std::shared_ptr<DATA::data_header>) override;
 
-    std::shared_ptr<DATA::data_header> provenance() const override;
+    std::shared_ptr<DATA::data_header> provenance() override;
     void setProvenance(std::shared_ptr<DATA::data_header>) override {};
 
-    bool isSyncronized() const override;
+    bool isSyncronized() override;
     void synchronize(uint8_t = 0) override;
 
     bool isEditable() const override;
 
-    uint16_t activeSlots() const override;
+    uint16_t activeSlots() override;
 
     // api for poly-source universes
     const std::vector<DATA::data_header> sources() const override;
@@ -85,14 +85,14 @@ public:
     void onSourceListChange(std::function<void()>) override;
 
     // DMX::Universe Overrides:
-    uint8_t slot(const uint16_t) const override;
+    uint8_t slot(const uint16_t) override;
     double rxRate() override;
 
 private:
     std::unordered_map<DATA::data_header, std::shared_ptr<Universe>> sources_;
     std::vector<std::function<void()>> cb_sourceListChange;  //!< list of calback functions
 
-    std::shared_ptr<Universe> dominant_() const;
+    std::shared_ptr<Universe> dominant_();
     bool hasSourceUniverse(const DATA::data_header&) const;
 };
 
diff --git a/protocol/sacn/universe.cpp b/protocol/sacn/universe.cpp
index 4e045f4..5332515 100644
--- a/protocol/sacn/universe.cpp
+++ b/protocol/sacn/universe.cpp
@@ -159,7 +159,7 @@ void Universe::setProvenance(std::shared_ptr<DATA::data_header> source)
  * @brief Universe::isSyncronized
  * @return
  */
-bool Universe::isSyncronized() const
+bool Universe::isSyncronized()
 {
   return (!sync_data_);
 };
@@ -223,7 +223,7 @@ std::shared_ptr<Universe> Universe::addNewSource(const DATA::data_header&)
  * @brief Universe::activeSlots
  * @return
  */
-uint16_t Universe::activeSlots() const
+uint16_t Universe::activeSlots()
 {
   return active_data_slots;
 }
@@ -291,7 +291,7 @@ void Universe::setValue (const uint16_t start, const uint16_t footprint,
  * @brief Universe::source
  * @return
  */
-std::shared_ptr<DATA::data_header> Universe::provenance() const
+std::shared_ptr<DATA::data_header> Universe::provenance()
 {
   return provenance_;
 }
diff --git a/protocol/sacn/universe.h b/protocol/sacn/universe.h
index bcf2364..b4c2aa9 100644
--- a/protocol/sacn/universe.h
+++ b/protocol/sacn/universe.h
@@ -53,15 +53,15 @@ public:
 
   virtual void set(ACN::PDU::Message<ACN::DMP::Pdu>, std::shared_ptr<DATA::data_header>);
 
-  virtual std::shared_ptr<DATA::data_header> provenance() const;
+  virtual std::shared_ptr<DATA::data_header> provenance();
   virtual void setProvenance(std::shared_ptr<DATA::data_header>);
 
-  virtual bool isSyncronized() const;
+  virtual bool isSyncronized();
   virtual void synchronize(uint8_t = 0);
 
   virtual bool isEditable() const;
 
-  virtual uint16_t activeSlots() const;
+  virtual uint16_t activeSlots();
 
   // api for poly-source universes
   virtual const std::vector<DATA::data_header> sources() const;