diff --git a/src/Helpers/BiMap.hpp b/src/Helpers/BiMap.hpp
index ffce6b4c..b83ce4c0 100644
--- a/src/Helpers/BiMap.hpp
+++ b/src/Helpers/BiMap.hpp
@@ -32,15 +32,15 @@ namespace Bloom
             }
         }
 
-        bool contains(TypeA key) const {
+        bool contains(const TypeA& key) const {
             return this->map.find(key) != this->map.end();
         }
 
-        bool contains(TypeB key) const {
+        bool contains(const TypeB& key) const {
             return this->flippedMap.find(key) != this->flippedMap.end();
         }
 
-        std::optional<TypeB> valueAt(TypeA key) const {
+        std::optional<TypeB> valueAt(const TypeA& key) const {
             std::optional<TypeB> output;
 
             if (this->contains(key)) {
@@ -50,7 +50,7 @@ namespace Bloom
             return output;
         }
 
-        std::optional<TypeA> valueAt(TypeB key) const {
+        std::optional<TypeA> valueAt(const TypeB& key) const {
             std::optional<TypeA> output;
 
             if (this->contains(key)) {
@@ -60,16 +60,15 @@ namespace Bloom
             return output;
         }
 
-        const TypeB& at(TypeA key) const {
+        const TypeB& at(const TypeA& key) const {
             return this->map.at(key);
         }
 
-        const TypeA& at(TypeB key) const {
-            return this->flippedMap.at(key);
+        const TypeA& at(const TypeB& key) const {
             return this->flippedMap.at(key)->first;
         }
 
-        std::unordered_map<TypeA, TypeB> getMap() const {
+        [[nodiscard]] std::unordered_map<TypeA, TypeB> getMap() const {
             return this->map;
         }