diff --git a/apps/openmw/mwdialogue/dialoguemanagerimp.cpp b/apps/openmw/mwdialogue/dialoguemanagerimp.cpp
index 6fac03e92..acfe7f5ee 100644
--- a/apps/openmw/mwdialogue/dialoguemanagerimp.cpp
+++ b/apps/openmw/mwdialogue/dialoguemanagerimp.cpp
@@ -325,8 +325,7 @@ namespace MWDialogue
             {
                 if (filter.responseAvailable (*iter))
                 {
-                    std::string lower = Misc::StringUtils::lowerCase(iter->mId);
-                    mActorKnownTopics.insert (lower);
+                    mActorKnownTopics.insert (iter->mId);
                 }
             }
         }
@@ -342,7 +341,7 @@ namespace MWDialogue
         for (const std::string& topic : mActorKnownTopics)
         {
             //does the player know the topic?
-            if (mKnownTopics.count(Misc::StringUtils::lowerCase(topic)))
+            if (mKnownTopics.count(topic))
                 keywordList.push_back(topic);
         }
 
diff --git a/apps/openmw/mwdialogue/dialoguemanagerimp.hpp b/apps/openmw/mwdialogue/dialoguemanagerimp.hpp
index d9c622120..a914d9a3e 100644
--- a/apps/openmw/mwdialogue/dialoguemanagerimp.hpp
+++ b/apps/openmw/mwdialogue/dialoguemanagerimp.hpp
@@ -8,6 +8,7 @@
 
 #include <components/compiler/streamerrorhandler.hpp>
 #include <components/translation/translation.hpp>
+#include <components/misc/stringops.hpp>
 
 #include "../mwworld/ptr.hpp"
 
@@ -22,13 +23,13 @@ namespace MWDialogue
 {
     class DialogueManager : public MWBase::DialogueManager
     {
-            std::set<std::string> mKnownTopics;// Those are the topics the player knows.
+            std::set<std::string, Misc::StringUtils::CiComp> mKnownTopics;// Those are the topics the player knows.
 
             // Modified faction reactions. <Faction1, <Faction2, Difference> >
             typedef std::map<std::string, std::map<std::string, int> > ModFactionReactionMap;
             ModFactionReactionMap mChangedFactionReaction;
 
-            std::set<std::string> mActorKnownTopics;
+            std::set<std::string, Misc::StringUtils::CiComp> mActorKnownTopics;
 
             Translation::Storage& mTranslationDataStorage;
             MWScript::CompilerContext mCompilerContext;