diff --git a/apps/esmtool/record.cpp b/apps/esmtool/record.cpp
index a142bac3c5..900c28164f 100644
--- a/apps/esmtool/record.cpp
+++ b/apps/esmtool/record.cpp
@@ -622,18 +622,15 @@ namespace EsmTool
         std::cout << "  Description: " << mData.mDescription << std::endl;
         std::cout << "  Playable: " << mData.mData.mIsPlayable << std::endl;
         std::cout << "  AI Services: " << Misc::StringUtils::format("0x%08X", mData.mData.mServices) << std::endl;
-        std::cout << "  Attribute1: " << attributeLabel(mData.mData.mAttribute[0]) << " (" << mData.mData.mAttribute[0]
-                  << ")" << std::endl;
-        std::cout << "  Attribute2: " << attributeLabel(mData.mData.mAttribute[1]) << " (" << mData.mData.mAttribute[1]
-                  << ")" << std::endl;
+        for (size_t i = 0; i < mData.mData.mAttribute.size(); ++i)
+            std::cout << "  Attribute" << (i + 1) << ": " << attributeLabel(mData.mData.mAttribute[i]) << " ("
+                      << mData.mData.mAttribute[i] << ")" << std::endl;
         std::cout << "  Specialization: " << specializationLabel(mData.mData.mSpecialization) << " ("
                   << mData.mData.mSpecialization << ")" << std::endl;
-        for (int i = 0; i != 5; i++)
-            std::cout << "  Minor Skill: " << skillLabel(mData.mData.mSkills[i][0]) << " (" << mData.mData.mSkills[i][0]
-                      << ")" << std::endl;
-        for (int i = 0; i != 5; i++)
-            std::cout << "  Major Skill: " << skillLabel(mData.mData.mSkills[i][1]) << " (" << mData.mData.mSkills[i][1]
-                      << ")" << std::endl;
+        for (const auto& skills : mData.mData.mSkills)
+            std::cout << "  Minor Skill: " << skillLabel(skills[0]) << " (" << skills[0] << ")" << std::endl;
+        for (const auto& skills : mData.mData.mSkills)
+            std::cout << "  Major Skill: " << skillLabel(skills[1]) << " (" << skills[1] << ")" << std::endl;
         std::cout << "  Deleted: " << mIsDeleted << std::endl;
     }
 
diff --git a/apps/opencs/model/tools/classcheck.cpp b/apps/opencs/model/tools/classcheck.cpp
index e608195a5f..0cbf5562fc 100644
--- a/apps/opencs/model/tools/classcheck.cpp
+++ b/apps/opencs/model/tools/classcheck.cpp
@@ -50,23 +50,32 @@ void CSMTools::ClassCheckStage::perform(int stage, CSMDoc::Messages& messages)
         messages.add(id, "Description of a playable class is missing", "", CSMDoc::Message::Severity_Warning);
 
     // test for invalid attributes
-    for (int i = 0; i < 2; ++i)
-        if (class_.mData.mAttribute[i] == -1)
+    std::map<int, int> attributeCount;
+    for (size_t i = 0; i < class_.mData.mAttribute.size(); ++i)
+    {
+        int attribute = class_.mData.mAttribute[i];
+        if (attribute == -1)
+            messages.add(id, "Attribute #" + std::to_string(i) + " is not set", {}, CSMDoc::Message::Severity_Error);
+        else
         {
-            messages.add(id, "Attribute #" + std::to_string(i) + " is not set", "", CSMDoc::Message::Severity_Error);
+            auto it = attributeCount.find(attribute);
+            if (it == attributeCount.end())
+                attributeCount.emplace(attribute, 1);
+            else
+            {
+                if (it->second == 1)
+                    messages.add(id, "Same attribute is listed twice", {}, CSMDoc::Message::Severity_Error);
+                ++it->second;
+            }
         }
-
-    if (class_.mData.mAttribute[0] == class_.mData.mAttribute[1] && class_.mData.mAttribute[0] != -1)
-    {
-        messages.add(id, "Same attribute is listed twice", "", CSMDoc::Message::Severity_Error);
     }
 
     // test for non-unique skill
     std::map<int, int> skills; // ID, number of occurrences
 
-    for (int i = 0; i < 5; ++i)
-        for (int i2 = 0; i2 < 2; ++i2)
-            ++skills[class_.mData.mSkills[i][i2]];
+    for (const auto& s : class_.mData.mSkills)
+        for (int skill : s)
+            ++skills[skill];
 
     for (auto& skill : skills)
         if (skill.second > 1)
diff --git a/apps/openmw/mwclass/npc.cpp b/apps/openmw/mwclass/npc.cpp
index 988de3c57f..2119434515 100644
--- a/apps/openmw/mwclass/npc.cpp
+++ b/apps/openmw/mwclass/npc.cpp
@@ -98,10 +98,9 @@ namespace
         // class bonus
         const ESM::Class* class_ = MWBase::Environment::get().getESMStore()->get<ESM::Class>().find(npc->mClass);
 
-        for (int i = 0; i < 2; ++i)
+        for (int attribute : class_->mData.mAttribute)
         {
-            int attribute = class_->mData.mAttribute[i];
-            if (attribute >= 0 && attribute < 8)
+            if (attribute >= 0 && attribute < ESM::Attribute::Length)
             {
                 creatureStats.setAttribute(attribute, creatureStats.getAttribute(attribute).getBase() + 10);
             }
@@ -121,14 +120,11 @@ namespace
 
                 // is this a minor or major skill?
                 float add = 0.2f;
-                for (int k = 0; k < 5; ++k)
+                for (const auto& skills : class_->mData.mSkills)
                 {
-                    if (class_->mData.mSkills[k][0] == j)
+                    if (skills[0] == j)
                         add = 0.5;
-                }
-                for (int k = 0; k < 5; ++k)
-                {
-                    if (class_->mData.mSkills[k][1] == j)
+                    if (skills[1] == j)
                         add = 1.0;
                 }
                 modifierSum += add;
@@ -149,8 +145,8 @@ namespace
         else if (class_->mData.mSpecialization == ESM::Class::Stealth)
             multiplier += 1;
 
-        if (class_->mData.mAttribute[0] == ESM::Attribute::Endurance
-            || class_->mData.mAttribute[1] == ESM::Attribute::Endurance)
+        if (std::find(class_->mData.mAttribute.begin(), class_->mData.mAttribute.end(), ESM::Attribute::Endurance)
+            != class_->mData.mAttribute.end())
             multiplier += 1;
 
         creatureStats.setHealth(floor(0.5f * (strength + endurance)) + multiplier * (creatureStats.getLevel() - 1));
@@ -183,9 +179,9 @@ namespace
         {
             int bonus = (i == 0) ? 10 : 25;
 
-            for (int i2 = 0; i2 < 5; ++i2)
+            for (const auto& skills : class_->mData.mSkills)
             {
-                int index = class_->mData.mSkills[i2][i];
+                int index = skills[i];
                 if (index >= 0 && index < ESM::Skill::Length)
                 {
                     npcStats.getSkill(index).setBase(npcStats.getSkill(index).getBase() + bonus);
@@ -206,10 +202,10 @@ namespace
             if (bonusIt != race->mData.mBonus.end())
                 raceBonus = bonusIt->mBonus;
 
-            for (int k = 0; k < 5; ++k)
+            for (const auto& skills : class_->mData.mSkills)
             {
                 // is this a minor or major skill?
-                if ((class_->mData.mSkills[k][0] == skillIndex) || (class_->mData.mSkills[k][1] == skillIndex))
+                if (std::find(skills.begin(), skills.end(), skillIndex) != skills.end())
                 {
                     majorMultiplier = 1.0f;
                     break;
diff --git a/apps/openmw/mwgui/charactercreation.cpp b/apps/openmw/mwgui/charactercreation.cpp
index e0ac94db93..586e8b766d 100644
--- a/apps/openmw/mwgui/charactercreation.cpp
+++ b/apps/openmw/mwgui/charactercreation.cpp
@@ -473,15 +473,14 @@ namespace MWGui
             klass.mRecordFlags = 0;
 
             std::vector<int> attributes = mCreateClassDialog->getFavoriteAttributes();
-            assert(attributes.size() == 2);
-            klass.mData.mAttribute[0] = attributes[0];
-            klass.mData.mAttribute[1] = attributes[1];
+            assert(attributes.size() == klass.mData.mAttribute.size());
+            std::copy(attributes.begin(), attributes.end(), klass.mData.mAttribute.begin());
 
             std::vector<ESM::Skill::SkillEnum> majorSkills = mCreateClassDialog->getMajorSkills();
             std::vector<ESM::Skill::SkillEnum> minorSkills = mCreateClassDialog->getMinorSkills();
-            assert(majorSkills.size() >= sizeof(klass.mData.mSkills) / sizeof(klass.mData.mSkills[0]));
-            assert(minorSkills.size() >= sizeof(klass.mData.mSkills) / sizeof(klass.mData.mSkills[0]));
-            for (size_t i = 0; i < sizeof(klass.mData.mSkills) / sizeof(klass.mData.mSkills[0]); ++i)
+            assert(majorSkills.size() >= klass.mData.mSkills.size());
+            assert(minorSkills.size() >= klass.mData.mSkills.size());
+            for (size_t i = 0; i < klass.mData.mSkills.size(); ++i)
             {
                 klass.mData.mSkills[i][1] = majorSkills[i];
                 klass.mData.mSkills[i][0] = minorSkills[i];
diff --git a/apps/openmw/mwgui/class.cpp b/apps/openmw/mwgui/class.cpp
index 864740aac5..1e7dafe92d 100644
--- a/apps/openmw/mwgui/class.cpp
+++ b/apps/openmw/mwgui/class.cpp
@@ -264,7 +264,7 @@ namespace MWGui
         ToolTips::createAttributeToolTip(mFavoriteAttribute[0], mFavoriteAttribute[0]->getAttributeId());
         ToolTips::createAttributeToolTip(mFavoriteAttribute[1], mFavoriteAttribute[1]->getAttributeId());
 
-        for (int i = 0; i < 5; ++i)
+        for (size_t i = 0; i < klass->mData.mSkills.size(); ++i)
         {
             mMinorSkill[i]->setSkillNumber(klass->mData.mSkills[i][0]);
             mMajorSkill[i]->setSkillNumber(klass->mData.mSkills[i][1]);
diff --git a/apps/openmw/mwgui/statswatcher.cpp b/apps/openmw/mwgui/statswatcher.cpp
index b03eab6869..6ad574a5a2 100644
--- a/apps/openmw/mwgui/statswatcher.cpp
+++ b/apps/openmw/mwgui/statswatcher.cpp
@@ -124,10 +124,11 @@ namespace MWGui
                     = MWBase::Environment::get().getESMStore()->get<ESM::Class>().find(watchedRecord->mClass);
                 setValue("class", cls->mName);
 
-                MWBase::WindowManager::SkillList majorSkills(5);
-                MWBase::WindowManager::SkillList minorSkills(5);
+                size_t size = cls->mData.mSkills.size();
+                MWBase::WindowManager::SkillList majorSkills(size);
+                MWBase::WindowManager::SkillList minorSkills(size);
 
-                for (int i = 0; i < 5; ++i)
+                for (size_t i = 0; i < size; ++i)
                 {
                     minorSkills[i] = cls->mData.mSkills[i][0];
                     majorSkills[i] = cls->mData.mSkills[i][1];
diff --git a/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp b/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
index 7f83f0ad8c..f5fa410725 100644
--- a/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
+++ b/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
@@ -191,10 +191,9 @@ namespace MWMechanics
         {
             const ESM::Class* class_ = esmStore.get<ESM::Class>().find(player->mClass);
 
-            for (int i = 0; i < 2; ++i)
+            for (int attribute : class_->mData.mAttribute)
             {
-                int attribute = class_->mData.mAttribute[i];
-                if (attribute >= 0 && attribute < 8)
+                if (attribute >= 0 && attribute < ESM::Attribute::Length)
                 {
                     creatureStats.setAttribute(attribute, creatureStats.getAttribute(attribute).getBase() + 10);
                 }
@@ -204,11 +203,11 @@ namespace MWMechanics
             {
                 int bonus = i == 0 ? 10 : 25;
 
-                for (int i2 = 0; i2 < 5; ++i2)
+                for (const auto& skills : class_->mData.mSkills)
                 {
-                    int index = class_->mData.mSkills[i2][i];
+                    int index = skills[i];
 
-                    if (index >= 0 && index < 27)
+                    if (index >= 0 && index < ESM::Skill::Length)
                     {
                         npcStats.getSkill(index).setBase(npcStats.getSkill(index).getBase() + bonus);
                     }
diff --git a/apps/openmw/mwmechanics/npcstats.cpp b/apps/openmw/mwmechanics/npcstats.cpp
index dd21a85305..9f1010194c 100644
--- a/apps/openmw/mwmechanics/npcstats.cpp
+++ b/apps/openmw/mwmechanics/npcstats.cpp
@@ -162,14 +162,14 @@ float MWMechanics::NpcStats::getSkillProgressRequirement(int skillIndex, const E
 
     float typeFactor = gmst.find("fMiscSkillBonus")->mValue.getFloat();
 
-    for (int i = 0; i < 5; ++i)
+    for (const auto& skills : class_.mData.mSkills)
     {
-        if (class_.mData.mSkills[i][0] == skillIndex)
+        if (skills[0] == skillIndex)
         {
             typeFactor = gmst.find("fMinorSkillBonus")->mValue.getFloat();
             break;
         }
-        else if (class_.mData.mSkills[i][1] == skillIndex)
+        else if (skills[1] == skillIndex)
         {
             typeFactor = gmst.find("fMajorSkillBonus")->mValue.getFloat();
             break;
@@ -235,15 +235,15 @@ void MWMechanics::NpcStats::increaseSkill(
 
     // is this a minor or major skill?
     int increase = gmst.find("iLevelupMiscMultAttriubte")->mValue.getInteger(); // Note: GMST has a typo
-    for (int k = 0; k < 5; ++k)
+    for (const auto& skills : class_.mData.mSkills)
     {
-        if (class_.mData.mSkills[k][0] == skillIndex)
+        if (skills[0] == skillIndex)
         {
             mLevelProgress += gmst.find("iLevelUpMinorMult")->mValue.getInteger();
             increase = gmst.find("iLevelUpMinorMultAttribute")->mValue.getInteger();
             break;
         }
-        else if (class_.mData.mSkills[k][1] == skillIndex)
+        else if (skills[1] == skillIndex)
         {
             mLevelProgress += gmst.find("iLevelUpMajorMult")->mValue.getInteger();
             increase = gmst.find("iLevelUpMajorMultAttribute")->mValue.getInteger();
diff --git a/components/esm3/loadclas.cpp b/components/esm3/loadclas.cpp
index a76855eb7f..9569c1a61d 100644
--- a/components/esm3/loadclas.cpp
+++ b/components/esm3/loadclas.cpp
@@ -13,18 +13,12 @@ namespace ESM
 
     int& Class::CLDTstruct::getSkill(int index, bool major)
     {
-        if (index < 0 || index >= 5)
-            throw std::logic_error("skill index out of range");
-
-        return mSkills[index][major ? 1 : 0];
+        return mSkills.at(index)[major ? 1 : 0];
     }
 
     int Class::CLDTstruct::getSkill(int index, bool major) const
     {
-        if (index < 0 || index >= 5)
-            throw std::logic_error("skill index out of range");
-
-        return mSkills[index][major ? 1 : 0];
+        return mSkills.at(index)[major ? 1 : 0];
     }
 
     void Class::load(ESMReader& esm, bool& isDeleted)
@@ -91,13 +85,12 @@ namespace ESM
         mName.clear();
         mDescription.clear();
 
-        mData.mAttribute[0] = mData.mAttribute[1] = 0;
+        mData.mAttribute.fill(0);
         mData.mSpecialization = 0;
         mData.mIsPlayable = 0;
         mData.mServices = 0;
 
-        for (int i = 0; i < 5; ++i)
-            for (int i2 = 0; i2 < 2; ++i2)
-                mData.mSkills[i][i2] = 0;
+        for (auto& skills : mData.mSkills)
+            skills.fill(0);
     }
 }
diff --git a/components/esm3/loadclas.hpp b/components/esm3/loadclas.hpp
index f47f0eb2b9..4f5e9a41fa 100644
--- a/components/esm3/loadclas.hpp
+++ b/components/esm3/loadclas.hpp
@@ -1,6 +1,7 @@
 #ifndef OPENMW_ESM_CLAS_H
 #define OPENMW_ESM_CLAS_H
 
+#include <array>
 #include <string>
 
 #include "components/esm/defs.hpp"
@@ -33,9 +34,9 @@ namespace ESM
 
         struct CLDTstruct
         {
-            int mAttribute[2]; // Attributes that get class bonus
+            std::array<int, 2> mAttribute; // Attributes that get class bonus
             int mSpecialization; // 0 = Combat, 1 = Magic, 2 = Stealth
-            int mSkills[5][2]; // Minor and major skills.
+            std::array<std::array<int, 2>, 5> mSkills; // Minor and major skills.
             int mIsPlayable; // 0x0001 - Playable class
             int mServices;