diff --git a/include/loot/metadata/conditional_metadata.h b/include/loot/metadata/conditional_metadata.h
index 4c80e11a..e069720a 100644
--- a/include/loot/metadata/conditional_metadata.h
+++ b/include/loot/metadata/conditional_metadata.h
@@ -39,7 +39,7 @@ public:
    * Construct a ConditionalMetadata object with an empty condition string.
    * @return A ConditionalMetadata object.
    */
-  LOOT_API ConditionalMetadata();
+  LOOT_API explicit ConditionalMetadata();
 
   /**
    * Construct a ConditionalMetadata object with a given condition string.
@@ -48,7 +48,7 @@ public:
    *         documentation.
    * @return A ConditionalMetadata object.
    */
-  LOOT_API ConditionalMetadata(const std::string& condition);
+  LOOT_API explicit ConditionalMetadata(const std::string& condition);
 
   /**
    * Check if the condition string is non-empty.
diff --git a/include/loot/metadata/file.h b/include/loot/metadata/file.h
index 97537db5..ef51b1cf 100644
--- a/include/loot/metadata/file.h
+++ b/include/loot/metadata/file.h
@@ -39,7 +39,7 @@ public:
    * Construct a File with blank name, display and condition strings.
    * @return A File object.
    */
-  LOOT_API File();
+  LOOT_API explicit File();
 
   /**
    * Construct a File with the given name, display name and condition strings.
@@ -51,7 +51,7 @@ public:
    *         The File's condition string.
    * @return A File object.
    */
-  LOOT_API File(const std::string& name,
+  LOOT_API explicit File(const std::string& name,
                 const std::string& display = "",
                 const std::string& condition = "");
 
diff --git a/include/loot/metadata/group.h b/include/loot/metadata/group.h
index bcfeed18..0e264c09 100644
--- a/include/loot/metadata/group.h
+++ b/include/loot/metadata/group.h
@@ -40,7 +40,7 @@ public:
    * load after.
    * @return A Group object.
    */
-  LOOT_API Group();
+  LOOT_API explicit Group();
 
   /**
    * Construct a Group with the given name, description and set of groups to
@@ -53,7 +53,7 @@ public:
    *         A description of the group.
    * @return A Group object.
    */
-  LOOT_API Group(const std::string& name,
+  LOOT_API explicit Group(const std::string& name,
                  const std::unordered_set<std::string>& afterGroups = {},
                  const std::string& description = "");
 
diff --git a/include/loot/metadata/location.h b/include/loot/metadata/location.h
index 7326d61d..f39ed68e 100644
--- a/include/loot/metadata/location.h
+++ b/include/loot/metadata/location.h
@@ -39,7 +39,7 @@ public:
    * Construct a Location with empty URL and name strings.
    * @return A Location object.
    */
-  LOOT_API Location();
+  LOOT_API explicit Location();
 
   /**
    * Construct a Location with the given URL and name.
@@ -49,7 +49,7 @@ public:
    *         A name for the URL, eg. the page or site name.
    * @return A Location object.
    */
-  LOOT_API Location(const std::string& url, const std::string& name = "");
+  LOOT_API explicit Location(const std::string& url, const std::string& name = "");
 
   /**
    * A less-than operator implemented with no semantics so that Location objects
diff --git a/include/loot/metadata/message.h b/include/loot/metadata/message.h
index b282ba45..6df64fa1 100644
--- a/include/loot/metadata/message.h
+++ b/include/loot/metadata/message.h
@@ -44,7 +44,7 @@ public:
    * strings.
    * @return A Message object.
    */
-  LOOT_API Message();
+  LOOT_API explicit Message();
 
   /**
    * Construct a Message object with the given type, English content and
@@ -57,7 +57,7 @@ public:
    *         A condition string.
    * @return A Message object.
    */
-  LOOT_API Message(const MessageType type,
+  LOOT_API explicit Message(const MessageType type,
                    const std::string& content,
                    const std::string& condition = "");
 
@@ -72,7 +72,7 @@ public:
    *         A condition string.
    * @return A Message object.
    */
-  LOOT_API Message(const MessageType type,
+  LOOT_API explicit Message(const MessageType type,
                    const std::vector<MessageContent>& content,
                    const std::string& condition = "");
 
diff --git a/include/loot/metadata/message_content.h b/include/loot/metadata/message_content.h
index 238a01b1..aefd4546 100644
--- a/include/loot/metadata/message_content.h
+++ b/include/loot/metadata/message_content.h
@@ -45,7 +45,7 @@ public:
    * Construct a MessageContent object with an empty English message string.
    * @return A MessageContent object.
    */
-  LOOT_API MessageContent();
+  LOOT_API explicit MessageContent();
 
   /**
    * Construct a Message object with the given text in the given language.
@@ -55,7 +55,7 @@ public:
    *         The language that the message is written in.
    * @return A MessageContent object.
    */
-  LOOT_API MessageContent(const std::string& text,
+  LOOT_API explicit MessageContent(const std::string& text,
                           const std::string& language = defaultLanguage);
 
   /**
diff --git a/include/loot/metadata/plugin_cleaning_data.h b/include/loot/metadata/plugin_cleaning_data.h
index f8d54596..d8045c1a 100644
--- a/include/loot/metadata/plugin_cleaning_data.h
+++ b/include/loot/metadata/plugin_cleaning_data.h
@@ -44,7 +44,7 @@ public:
    * and no info.
    * @return A PluginCleaningData object.
    */
-  LOOT_API PluginCleaningData();
+  LOOT_API explicit PluginCleaningData();
 
   /**
    * Construct a PluginCleaningData object with the given CRC and utility,
@@ -56,7 +56,7 @@ public:
    *         The utility that the plugin cleanliness was checked with.
    * @return A PluginCleaningData object.
    */
-  LOOT_API PluginCleaningData(uint32_t crc, const std::string& utility);
+  LOOT_API explicit PluginCleaningData(uint32_t crc, const std::string& utility);
 
   /**
    * Construct a PluginCleaningData object with the given values.
@@ -75,7 +75,7 @@ public:
    *         The number of deleted navmeshes found in the plugin.
    * @return A PluginCleaningData object.
    */
-  LOOT_API PluginCleaningData(uint32_t crc,
+  LOOT_API explicit PluginCleaningData(uint32_t crc,
                               const std::string& utility,
                               const std::vector<MessageContent>& info,
                               unsigned int itm,
diff --git a/include/loot/metadata/plugin_metadata.h b/include/loot/metadata/plugin_metadata.h
index 88c819df..91191817 100644
--- a/include/loot/metadata/plugin_metadata.h
+++ b/include/loot/metadata/plugin_metadata.h
@@ -49,7 +49,7 @@ public:
    * Construct a PluginMetadata object with a blank plugin name and no metadata.
    * @return A PluginMetadata object.
    */
-  LOOT_API PluginMetadata();
+  LOOT_API explicit PluginMetadata();
 
   /**
    * Construct a PluginMetadata object with no metadata for a plugin with the
@@ -58,7 +58,7 @@ public:
    *         The filename of the plugin that the object is constructed for.
    * @return A PluginMetadata object.
    */
-  LOOT_API PluginMetadata(const std::string& name);
+  LOOT_API explicit PluginMetadata(const std::string& name);
 
   /**
    * Merge metadata from the given PluginMetadata object into this object.
diff --git a/include/loot/metadata/tag.h b/include/loot/metadata/tag.h
index f3b9fdc4..a586f0f2 100644
--- a/include/loot/metadata/tag.h
+++ b/include/loot/metadata/tag.h
@@ -40,7 +40,7 @@ public:
    * an empty condition string.
    * @return A Tag object.
    */
-  LOOT_API Tag();
+  LOOT_API explicit Tag();
 
   /**
    * Construct a Tag object with the given name, for addition or removal, with
@@ -53,7 +53,7 @@ public:
    *         A condition string.
    * @return A Tag object.
    */
-  LOOT_API Tag(const std::string& tag,
+  LOOT_API explicit Tag(const std::string& tag,
                const bool isAddition = true,
                const std::string& condition = "");
 
diff --git a/include/loot/struct/masterlist_info.h b/include/loot/struct/masterlist_info.h
index a19582b8..c46fd942 100644
--- a/include/loot/struct/masterlist_info.h
+++ b/include/loot/struct/masterlist_info.h
@@ -32,7 +32,7 @@ namespace loot {
  *        revision.
  */
 struct MasterlistInfo {
-  inline MasterlistInfo() : is_modified(false) {}
+  inline explicit MasterlistInfo() : is_modified(false) {}
 
   /**
    * @brief The revision hash for the masterlist. If the masterlist doesn't
diff --git a/include/loot/vertex.h b/include/loot/vertex.h
index d0cdc60a..861d652c 100644
--- a/include/loot/vertex.h
+++ b/include/loot/vertex.h
@@ -42,14 +42,14 @@ public:
    * @brief Construct a Vertex with the given name and no out edge.
    * @param name The name of the plugin or group that this vertex represents.
    */
-  LOOT_API Vertex(std::string name);
+  LOOT_API explicit Vertex(std::string name);
 
   /**
    * @brief Construct a Vertex with the given name and out edge type.
    * @param name The name of the plugin or group that this vertex represents.
    * @param outEdgeType The type of the edge going out from this vertex.
    */
-  LOOT_API Vertex(std::string name, EdgeType outEdgeType);
+  LOOT_API explicit Vertex(std::string name, EdgeType outEdgeType);
 
   /**
    * @brief Get the name of the plugin or group.
diff --git a/src/api/api_database.cpp b/src/api/api_database.cpp
index d7ce3709..f056fb93 100644
--- a/src/api/api_database.cpp
+++ b/src/api/api_database.cpp
@@ -169,7 +169,7 @@ std::unordered_set<Group> ApiDatabase::GetGroups(bool includeUserMetadata) const
 
   auto userlistGroups = userlist_.Groups();
   for (const auto& group : masterlist_.Groups()) {
-    auto userlistGroup = userlistGroups.find(group.GetName());
+    auto userlistGroup = userlistGroups.find(group);
     if (userlistGroup != userlistGroups.end()) {
       auto afterGroups = group.GetAfterGroups();
       auto userlistAfterGroups = userlistGroup->GetAfterGroups();
diff --git a/src/api/api_database.h b/src/api/api_database.h
index b9ed7c3c..680bdbbc 100644
--- a/src/api/api_database.h
+++ b/src/api/api_database.h
@@ -40,7 +40,7 @@
 
 namespace loot {
 struct ApiDatabase : public DatabaseInterface {
-  ApiDatabase(std::shared_ptr<ConditionEvaluator> conditionEvaluator);
+  explicit ApiDatabase(std::shared_ptr<ConditionEvaluator> conditionEvaluator);
 
   void LoadLists(const std::filesystem::path& masterlist_path,
                  const std::filesystem::path& userlist_path = "");
diff --git a/src/api/game/game.h b/src/api/game/game.h
index 85710dbf..a06998a2 100644
--- a/src/api/game/game.h
+++ b/src/api/game/game.h
@@ -36,7 +36,7 @@
 namespace loot {
 class Game : public GameInterface {
 public:
-  Game(const GameType gameType,
+  explicit Game(const GameType gameType,
        const std::filesystem::path& gamePath,
        const std::filesystem::path& gameLocalDataPath = "");
 
diff --git a/src/api/game/game_cache.h b/src/api/game/game_cache.h
index 6127776a..caf3a851 100644
--- a/src/api/game/game_cache.h
+++ b/src/api/game/game_cache.h
@@ -34,8 +34,8 @@
 namespace loot {
 class GameCache {
 public:
-  GameCache();
-  GameCache(const GameCache& cache);
+  explicit GameCache();
+  explicit GameCache(const GameCache& cache);
 
   GameCache& operator=(const GameCache& cache);
 
diff --git a/src/api/game/load_order_handler.h b/src/api/game/load_order_handler.h
index c073d2b4..5073453c 100644
--- a/src/api/game/load_order_handler.h
+++ b/src/api/game/load_order_handler.h
@@ -38,7 +38,7 @@
 namespace loot {
 class LoadOrderHandler {
 public:
-  LoadOrderHandler();
+  explicit LoadOrderHandler();
   ~LoadOrderHandler();
 
   void Init(const GameType& game,
diff --git a/src/api/helpers/git_helper.h b/src/api/helpers/git_helper.h
index 9a242720..129ad113 100644
--- a/src/api/helpers/git_helper.h
+++ b/src/api/helpers/git_helper.h
@@ -34,7 +34,7 @@
 namespace loot {
 class GitHelper {
 public:
-  GitHelper();
+  explicit GitHelper();
 
   void InitialiseOptions(const std::string& branch,
                          const std::string& filenameToCheckout);
diff --git a/src/api/helpers/logging.h b/src/api/helpers/logging.h
index 0ea37323..19e52c56 100644
--- a/src/api/helpers/logging.h
+++ b/src/api/helpers/logging.h
@@ -40,7 +40,7 @@ inline std::shared_ptr<spdlog::logger> getLogger() {
 
 class SpdLoggingSink : public spdlog::sinks::base_sink<std::mutex> {
 public:
-  SpdLoggingSink(std::function<void(LogLevel, const char*)> callback) {
+  explicit SpdLoggingSink(std::function<void(LogLevel, const char*)> callback) {
     this->callback = callback;
   }
 
diff --git a/src/api/metadata/condition_evaluator.h b/src/api/metadata/condition_evaluator.h
index ff12483f..85117ffb 100644
--- a/src/api/metadata/condition_evaluator.h
+++ b/src/api/metadata/condition_evaluator.h
@@ -38,7 +38,7 @@
 namespace loot {
 class ConditionEvaluator {
 public:
-  ConditionEvaluator(const GameType gameType,
+  explicit ConditionEvaluator(const GameType gameType,
     const std::filesystem::path& dataPath);
 
   bool Evaluate(const std::string& condition);
diff --git a/src/api/plugin.h b/src/api/plugin.h
index f08923ab..67944f45 100644
--- a/src/api/plugin.h
+++ b/src/api/plugin.h
@@ -43,7 +43,7 @@ class GameCache;
 
 class Plugin : public PluginInterface {
 public:
-  Plugin(const GameType gameType,
+  explicit Plugin(const GameType gameType,
          std::shared_ptr<GameCache> gameCache,
          std::filesystem::path pluginPath,
          const bool headerOnly);
diff --git a/src/api/sorting/plugin_sorting_data.h b/src/api/sorting/plugin_sorting_data.h
index 4aebf427..5a522621 100644
--- a/src/api/sorting/plugin_sorting_data.h
+++ b/src/api/sorting/plugin_sorting_data.h
@@ -31,7 +31,7 @@
 namespace loot {
 class PluginSortingData {
 public:
-  PluginSortingData(const Plugin& plugin,
+  explicit PluginSortingData(const Plugin& plugin,
                     const PluginMetadata& masterlistMetadata,
                     const PluginMetadata& userMetadata,
                     const std::vector<std::string>& loadOrder,
diff --git a/src/tests/api/internals/metadata/plugin_metadata_test.h b/src/tests/api/internals/metadata/plugin_metadata_test.h
index 91984506..7dd73391 100644
--- a/src/tests/api/internals/metadata/plugin_metadata_test.h
+++ b/src/tests/api/internals/metadata/plugin_metadata_test.h
@@ -290,7 +290,8 @@ TEST_P(PluginMetadataTest, newMetadataShouldUseSourcePluginEnabledState) {
   EXPECT_FALSE(newMetadata.IsEnabled());
 }
 
-TEST_P(PluginMetadataTest, newMetadataShouldUseSourcePluginGroupExplicitlyIfItIsExplicit) {
+TEST_P(PluginMetadataTest,
+       newMetadataShouldUseSourcePluginGroupExplicitlyIfItIsExplicit) {
   PluginMetadata plugin1;
   PluginMetadata plugin2;
 
@@ -302,8 +303,9 @@ TEST_P(PluginMetadataTest, newMetadataShouldUseSourcePluginGroupExplicitlyIfItIs
   EXPECT_EQ("group1", newMetadata.GetGroup().value());
 }
 
-TEST_P(PluginMetadataTest,
-       newMetadataShouldUseGivenPluginGroupImplicitlyIfTheSourcePluginGroupIsNotExplicit) {
+TEST_P(
+    PluginMetadataTest,
+    newMetadataShouldUseGivenPluginGroupImplicitlyIfTheSourcePluginGroupIsNotExplicit) {
   PluginMetadata plugin1;
   PluginMetadata plugin2;
 
@@ -314,9 +316,8 @@ TEST_P(PluginMetadataTest,
   EXPECT_FALSE(newMetadata.GetGroup());
 }
 
-TEST_P(
-    PluginMetadataTest,
-    newMetadataShouldUseSourcePluginGroupImplicitlyIfTheGroupsAreTheSame) {
+TEST_P(PluginMetadataTest,
+       newMetadataShouldUseSourcePluginGroupImplicitlyIfTheGroupsAreTheSame) {
   PluginMetadata plugin1;
   PluginMetadata plugin2;
 
@@ -457,8 +458,10 @@ TEST_P(PluginMetadataTest, simpleMessagesShouldReturnMessagesAsSimpleMessages) {
   plugin.SetMessages({
       Message(MessageType::say, "content1"),
       Message(MessageType::warn,
-              {{"content2", french},
-               {"other content2", MessageContent::defaultLanguage}}),
+              std::vector<MessageContent>(
+                  {MessageContent("content2", french),
+                   MessageContent("other content2",
+                                  MessageContent::defaultLanguage)})),
       Message(MessageType::error, "content3"),
   });
 
@@ -985,8 +988,7 @@ TEST_P(PluginMetadataTest,
   PluginMetadata plugin = node.as<PluginMetadata>();
 
   EXPECT_EQ("Blank\\.esp", plugin.GetName());
-  EXPECT_EQ(std::set<PluginCleaningData>(
-                {PluginCleaningData(5, "utility")}),
+  EXPECT_EQ(std::set<PluginCleaningData>({PluginCleaningData(5, "utility")}),
             plugin.GetCleanInfo());
 }