diff --git a/src/entity_manager/topology.cpp b/src/entity_manager/topology.cpp
index add9ce0..1828ed7 100644
--- a/src/entity_manager/topology.cpp
+++ b/src/entity_manager/topology.cpp
@@ -51,10 +51,10 @@
     }
 }
 
-std::unordered_map<std::string, std::vector<Association>> Topology::getAssocs(
+std::unordered_map<std::string, std::set<Association>> Topology::getAssocs(
     const std::map<Path, BoardName>& boards)
 {
-    std::unordered_map<std::string, std::vector<Association>> result;
+    std::unordered_map<std::string, std::set<Association>> result;
 
     // look at each upstream port type
     for (const auto& upstreamPortPair : upstreamPorts)
@@ -77,12 +77,12 @@
                     // The downstream path must be one we care about.
                     if (boards.contains(downstream))
                     {
-                        result[downstream].emplace_back("contained_by",
-                                                        "containing", upstream);
+                        result[downstream].insert(
+                            {"contained_by", "containing", upstream});
                         if (powerPaths.contains(downstream))
                         {
-                            result[downstream].emplace_back(
-                                "powering", "powered_by", upstream);
+                            result[downstream].insert(
+                                {"powering", "powered_by", upstream});
                         }
                     }
                 }
diff --git a/src/entity_manager/topology.hpp b/src/entity_manager/topology.hpp
index 7317b3a..3ca214d 100644
--- a/src/entity_manager/topology.hpp
+++ b/src/entity_manager/topology.hpp
@@ -15,7 +15,7 @@
     void addBoard(const std::string& path, const std::string& boardType,
                   const std::string& boardName,
                   const nlohmann::json& exposesItem);
-    std::unordered_map<std::string, std::vector<Association>> getAssocs(
+    std::unordered_map<std::string, std::set<Association>> getAssocs(
         const std::map<std::string, std::string>& boards);
     void remove(const std::string& boardName);