diff --git a/apps/openmw/mwgui/spellbuyingwindow.cpp b/apps/openmw/mwgui/spellbuyingwindow.cpp
index 11f0904943..40fcf2988a 100644
--- a/apps/openmw/mwgui/spellbuyingwindow.cpp
+++ b/apps/openmw/mwgui/spellbuyingwindow.cpp
@@ -94,9 +94,6 @@ namespace MWGui
         mPtr = actor;
         clearSpells();
 
-        MWWorld::Ptr player = MWBase::Environment::get().getWorld()->getPlayer().getPlayer();
-
-        MWMechanics::Spells& playerSpells = MWWorld::Class::get (player).getCreatureStats (player).getSpells();
         MWMechanics::Spells& merchantSpells = MWWorld::Class::get (actor).getCreatureStats (actor).getSpells();
 
         for (MWMechanics::Spells::TIterator iter = merchantSpells.begin(); iter!=merchantSpells.end(); ++iter)
@@ -107,8 +104,8 @@ namespace MWGui
             if (spell->mData.mType!=ESM::Spell::ST_Spell)
                 continue; // don't try to sell diseases, curses or powers
 
-            if (std::find (playerSpells.begin(), playerSpells.end(), *iter)!=playerSpells.end())
-                continue; // we have that spell already
+            if (playerHasSpell(iter->first))
+                continue;
 
             addSpell (iter->first);
         }
@@ -118,6 +115,18 @@ namespace MWGui
         mSpellsView->setCanvasSize (MyGUI::IntSize(mSpellsView->getWidth(), std::max(mSpellsView->getHeight(), mCurrentY)));
     }
 
+    bool SpellBuyingWindow::playerHasSpell(const std::string &id)
+    {
+        MWWorld::Ptr player = MWBase::Environment::get().getWorld()->getPlayer().getPlayer();
+        MWMechanics::Spells& playerSpells = MWWorld::Class::get (player).getCreatureStats (player).getSpells();
+        for (MWMechanics::Spells::TIterator it = playerSpells.begin(); it != playerSpells.end(); ++it)
+        {
+            if (Misc::StringUtils::ciEqual(id, it->first))
+                return true;
+        }
+        return false;
+    }
+
     void SpellBuyingWindow::onSpellButtonClick(MyGUI::Widget* _sender)
     {
         int price = *_sender->getUserData<int>();
diff --git a/apps/openmw/mwgui/spellbuyingwindow.hpp b/apps/openmw/mwgui/spellbuyingwindow.hpp
index 1d0ac28e01..c4988fff35 100644
--- a/apps/openmw/mwgui/spellbuyingwindow.hpp
+++ b/apps/openmw/mwgui/spellbuyingwindow.hpp
@@ -47,6 +47,8 @@ namespace MWGui
             void updateLabels();
 
             virtual void onReferenceUnavailable();
+
+            bool playerHasSpell (const std::string& id);
     };
 }