diff --git a/src/server/game/Entities/Unit/Unit.h b/src/server/game/Entities/Unit/Unit.h
index f8dd29b6b..a897fcca8 100644
--- a/src/server/game/Entities/Unit/Unit.h
+++ b/src/server/game/Entities/Unit/Unit.h
@@ -1451,10 +1451,10 @@ public:
     void CleanupBeforeRemoveFromMap(bool finalCleanup);
     void CleanupsBeforeDelete(bool finalCleanup = true) override;                        // used in ~Creature/~Player (or before mass creature delete to remove cross-references to already deleted units)
 
-    DiminishingLevels GetDiminishing(DiminishingGroup  group);
+    DiminishingLevels GetDiminishing(DiminishingGroup group);
     void IncrDiminishing(DiminishingGroup group);
-    float ApplyDiminishingToDuration(DiminishingGroup  group, int32& duration, Unit* caster, DiminishingLevels Level, int32 limitduration);
-    void ApplyDiminishingAura(DiminishingGroup  group, bool apply);
+    float ApplyDiminishingToDuration(DiminishingGroup group, int32& duration, Unit* caster, DiminishingLevels Level, int32 limitduration);
+    void ApplyDiminishingAura(DiminishingGroup group, bool apply);
     void ClearDiminishings() { m_Diminishing.clear(); }
 
     // target dependent range checks
diff --git a/src/server/game/Spells/Spell.cpp b/src/server/game/Spells/Spell.cpp
index a4da71b16..6598a2af9 100644
--- a/src/server/game/Spells/Spell.cpp
+++ b/src/server/game/Spells/Spell.cpp
@@ -2879,10 +2879,15 @@ SpellMissInfo Spell::DoSpellHitOnUnit(Unit* unit, uint32 effectMask, bool scaleA
         uint32 flagsExtra = unit->GetTypeId() == TYPEID_UNIT ? unit->ToCreature()->GetCreatureTemplate()->flags_extra : 0;
 
         // Increase Diminishing on unit, current informations for actually casts will use values above
-        if ((type == DRTYPE_PLAYER && (
-                    unit->GetCharmerOrOwnerPlayerOrPlayerItself() || flagsExtra & CREATURE_FLAG_EXTRA_ALL_DIMINISH || (m_diminishGroup == DIMINISHING_TAUNT && (flagsExtra & CREATURE_FLAG_EXTRA_OBEYS_TAUNT_DIMINISHING_RETURNS))
-                )) || type == DRTYPE_ALL)
-            unit->IncrDiminishing(m_diminishGroup);
+        if ((type == DRTYPE_PLAYER && (unit->IsCharmedOwnedByPlayerOrPlayer() || flagsExtra & CREATURE_FLAG_EXTRA_ALL_DIMINISH ||
+            (m_diminishGroup == DIMINISHING_TAUNT && (flagsExtra & CREATURE_FLAG_EXTRA_OBEYS_TAUNT_DIMINISHING_RETURNS)))) || type == DRTYPE_ALL)
+        {
+            // Do not apply diminish return if caster is NPC
+            if (m_caster->IsCharmedOwnedByPlayerOrPlayer())
+            {
+                unit->IncrDiminishing(m_diminishGroup);
+            }
+        }
     }
 
     if (m_caster != unit && m_caster->IsHostileTo(unit) && !m_spellInfo->IsPositive() && !m_triggeredByAuraSpell && !m_spellInfo->HasAttribute(SPELL_ATTR0_CU_DONT_BREAK_STEALTH))