diff --git a/apps/openmw/mwmechanics/alchemy.cpp b/apps/openmw/mwmechanics/alchemy.cpp
index 58c42ddb81..1d43c71ffa 100644
--- a/apps/openmw/mwmechanics/alchemy.cpp
+++ b/apps/openmw/mwmechanics/alchemy.cpp
@@ -44,6 +44,8 @@ std::set<MWMechanics::EffectKey> MWMechanics::Alchemy::listEffects() const
         {
             const MWWorld::LiveCellRef<ESM::Ingredient> *ingredient = iter->get<ESM::Ingredient>();
 
+            std::set<EffectKey> seenEffects;
+
             for (int i=0; i<4; ++i)
                 if (ingredient->mBase->mData.mEffectID[i]!=-1)
                 {
@@ -51,7 +53,8 @@ std::set<MWMechanics::EffectKey> MWMechanics::Alchemy::listEffects() const
                         ingredient->mBase->mData.mEffectID[i], ingredient->mBase->mData.mSkills[i]!=-1 ?
                         ingredient->mBase->mData.mSkills[i] : ingredient->mBase->mData.mAttributes[i]);
 
-                    ++effects[key];
+                    if (seenEffects.insert(key).second)
+                        ++effects[key];
                 }
         }
     }