diff --git a/apps/openmw/mwbase/mechanicsmanager.hpp b/apps/openmw/mwbase/mechanicsmanager.hpp
index b29859781..87f1104db 100644
--- a/apps/openmw/mwbase/mechanicsmanager.hpp
+++ b/apps/openmw/mwbase/mechanicsmanager.hpp
@@ -97,7 +97,7 @@ namespace MWBase
             virtual int getBarterOffer(const MWWorld::Ptr& ptr,int basePrice, bool buying) = 0;
             ///< This is used by every service to determine the price of objects given the trading skills of the player and NPC.
 
-            virtual int getDerivedDisposition(const MWWorld::Ptr& ptr, bool addTemporaryDispositionChange = false) = 0;
+            virtual int getDerivedDisposition(const MWWorld::Ptr& ptr, bool addTemporaryDispositionChange = true) = 0;
             ///< Calculate the diposition of an NPC toward the player.
 
             virtual int countDeaths (const std::string& id) const = 0;
diff --git a/apps/openmw/mwdialogue/dialoguemanagerimp.cpp b/apps/openmw/mwdialogue/dialoguemanagerimp.cpp
index c99e86c2d..393d2dc98 100644
--- a/apps/openmw/mwdialogue/dialoguemanagerimp.cpp
+++ b/apps/openmw/mwdialogue/dialoguemanagerimp.cpp
@@ -535,7 +535,7 @@ namespace MWDialogue
         mPermanentDispositionChange += perm;
 
         // change temp disposition so that final disposition is between 0...100
-        float curDisp = static_cast<float>(MWBase::Environment::get().getMechanicsManager()->getDerivedDisposition(mActor));
+        float curDisp = static_cast<float>(MWBase::Environment::get().getMechanicsManager()->getDerivedDisposition(mActor, false));
         if (curDisp + mTemporaryDispositionChange < 0)
             mTemporaryDispositionChange = -curDisp;
         else if (curDisp + mTemporaryDispositionChange > 100)
diff --git a/apps/openmw/mwdialogue/filter.cpp b/apps/openmw/mwdialogue/filter.cpp
index 223690a71..99e689411 100644
--- a/apps/openmw/mwdialogue/filter.cpp
+++ b/apps/openmw/mwdialogue/filter.cpp
@@ -145,7 +145,7 @@ bool MWDialogue::Filter::testDisposition (const ESM::DialInfo& info, bool invert
     if (isCreature)
         return true;
 
-    int actorDisposition = MWBase::Environment::get().getMechanicsManager()->getDerivedDisposition(mActor, true);
+    int actorDisposition = MWBase::Environment::get().getMechanicsManager()->getDerivedDisposition(mActor);
     // For service refusal, the disposition check is inverted. However, a value of 0 still means "always succeed".
     return invert ? (info.mData.mDisposition == 0 || actorDisposition < info.mData.mDisposition)
                   : (actorDisposition >= info.mData.mDisposition);
diff --git a/apps/openmw/mwgui/dialogue.cpp b/apps/openmw/mwgui/dialogue.cpp
index 76f39f5e7..40ec57731 100644
--- a/apps/openmw/mwgui/dialogue.cpp
+++ b/apps/openmw/mwgui/dialogue.cpp
@@ -640,7 +640,7 @@ namespace MWGui
         if(mMainWidget->getVisible() && mEnabled && mPtr.getTypeName() == typeid(ESM::NPC).name())
         {
             int disp = std::max(0, std::min(100,
-                MWBase::Environment::get().getMechanicsManager()->getDerivedDisposition(mPtr, true)));
+                MWBase::Environment::get().getMechanicsManager()->getDerivedDisposition(mPtr)));
             mDispositionBar->setProgressRange(100);
             mDispositionBar->setProgressPosition(disp);
             mDispositionText->setCaption(MyGUI::utility::toString(disp)+std::string("/100"));
diff --git a/apps/openmw/mwgui/tradewindow.cpp b/apps/openmw/mwgui/tradewindow.cpp
index d692c8b09..14c78cf0f 100644
--- a/apps/openmw/mwgui/tradewindow.cpp
+++ b/apps/openmw/mwgui/tradewindow.cpp
@@ -346,7 +346,7 @@ namespace MWGui
             else
                 d = int(100 * (b - a) / a);
 
-            int clampedDisposition = std::max(0, std::min(MWBase::Environment::get().getMechanicsManager()->getDerivedDisposition(mPtr, true),100));
+            int clampedDisposition = std::max(0, std::min(MWBase::Environment::get().getMechanicsManager()->getDerivedDisposition(mPtr),100));
 
             const MWMechanics::CreatureStats &sellerStats = mPtr.getClass().getCreatureStats(mPtr);
             const MWMechanics::CreatureStats &playerStats = player.getClass().getCreatureStats(player);
diff --git a/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp b/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
index e6a92b9ea..7cfb937c8 100644
--- a/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
+++ b/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
@@ -581,7 +581,7 @@ namespace MWMechanics
         mUpdatePlayer = true;
     }
 
-    int MechanicsManager::getDerivedDisposition(const MWWorld::Ptr& ptr, bool addTemporaryDispositionChange/* = false */)
+    int MechanicsManager::getDerivedDisposition(const MWWorld::Ptr& ptr, bool addTemporaryDispositionChange)
     {
         const MWMechanics::NpcStats& npcSkill = ptr.getClass().getNpcStats(ptr);
         float x = static_cast<float>(npcSkill.getBaseDisposition());
@@ -672,7 +672,7 @@ namespace MWMechanics
 
         // I suppose the temporary disposition change (second param to getDerivedDisposition()) _has_ to be considered here,
         // otherwise one would get different prices when exiting and re-entering the dialogue window...
-        int clampedDisposition = std::max(0, std::min(getDerivedDisposition(ptr, true),100));
+        int clampedDisposition = std::max(0, std::min(getDerivedDisposition(ptr),100));
         float a = static_cast<float>(std::min(playerStats.getSkill(ESM::Skill::Mercantile).getModified(), 100));
         float b = std::min(0.1f * playerStats.getAttribute(ESM::Attribute::Luck).getModified(), 10.f);
         float c = std::min(0.2f * playerStats.getAttribute(ESM::Attribute::Personality).getModified(), 10.f);
@@ -719,7 +719,7 @@ namespace MWMechanics
         float playerRating1, playerRating2, playerRating3;
         getPersuasionRatings(playerStats, playerRating1, playerRating2, playerRating3, true);
 
-        int currentDisposition = std::min(100, std::max(0, int(getDerivedDisposition(npc) + currentTemporaryDispositionDelta)));
+        int currentDisposition = std::min(100, std::max(0, int(getDerivedDisposition(npc, false) + currentTemporaryDispositionDelta)));
 
         float d = 1 - 0.02f * abs(currentDisposition - 50);
         float target1 = d * (playerRating1 - npcRating1 + 50);
@@ -1547,7 +1547,7 @@ namespace MWMechanics
     {
         int disposition = 50;
         if (ptr.getClass().isNpc())
-            disposition = getDerivedDisposition(ptr);
+            disposition = getDerivedDisposition(ptr, false);
 
         int fight = std::max(0, ptr.getClass().getCreatureStats(ptr).getAiSetting(CreatureStats::AI_Fight).getModified()
                 + static_cast<int>(getFightDistanceBias(ptr, target) + getFightDispositionBias(static_cast<float>(disposition))));