diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 14e6a85..8695812 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -1,7 +1,7 @@
 includes:
     - ./vendor/larastan/larastan/extension.neon
 parameters:
-    level: 6
+    level: 7
     paths:
         - src
     treatPhpDocTypesAsCertain: false
diff --git a/src/Eloquent/CompositeKey.php b/src/Eloquent/CompositeKey.php
index dac3179..2c2af8e 100644
--- a/src/Eloquent/CompositeKey.php
+++ b/src/Eloquent/CompositeKey.php
@@ -14,6 +14,6 @@ class CompositeKey
      */
     public function __construct(...$columns)
     {
-        $this->columns = $columns;
+        $this->columns = array_values($columns);
     }
 }
diff --git a/src/Eloquent/Relations/ThirdParty/LaravelHasManyMerged/HasManyMerged.php b/src/Eloquent/Relations/ThirdParty/LaravelHasManyMerged/HasManyMerged.php
index afbb5c3..36717bb 100644
--- a/src/Eloquent/Relations/ThirdParty/LaravelHasManyMerged/HasManyMerged.php
+++ b/src/Eloquent/Relations/ThirdParty/LaravelHasManyMerged/HasManyMerged.php
@@ -20,15 +20,13 @@ class HasManyMerged extends Base implements ConcatenableRelation
     /**
      * Append the relation's through parents, foreign and local keys to a deep relationship.
      *
-     * @param list<\Illuminate\Database\Eloquent\Model> $through
-     * @param list<array{0: string,
-     *     1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $foreignKeys
-     * @param list<array{0: string,
-     *     1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $localKeys
+     * @param non-empty-list<string> $through
+     * @param non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $foreignKeys
+     * @param non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $localKeys
      * @param int $position
-     * @return array{0: list<string>,
-     *     1: list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>,
-     *     2: list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>}
+     * @return array{0: non-empty-list<string>,
+     *     1: non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null>,
+     *     2: non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null>}
      */
     public function appendToDeepRelationship(array $through, array $foreignKeys, array $localKeys, int $position): array
     {
diff --git a/src/Eloquent/Relations/Traits/ExecutesQueries.php b/src/Eloquent/Relations/Traits/ExecutesQueries.php
index 6a1745d..0cdf8d4 100644
--- a/src/Eloquent/Relations/Traits/ExecutesQueries.php
+++ b/src/Eloquent/Relations/Traits/ExecutesQueries.php
@@ -23,12 +23,7 @@ public function getResults()
         return parent::getResults();
     }
 
-    /**
-     * Execute the query as a "select" statement.
-     *
-     * @param string|list<string> $columns
-     * @return \Illuminate\Database\Eloquent\Collection<int, \Illuminate\Database\Eloquent\Model>
-     */
+    /** @inheritDoc */
     public function get($columns = ['*'])
     {
         $models = parent::get($columns);
@@ -111,13 +106,7 @@ public function cursorPaginate($perPage = null, $columns = ['*'], $cursorName =
         });
     }
 
-    /**
-     * Chunk the results of the query.
-     *
-     * @param int $count
-     * @param callable $callback
-     * @return bool
-     */
+    /** @inheritDoc */
     public function chunk($count, callable $callback)
     {
         return $this->prepareQueryBuilder()->chunk($count, function (Collection $results) use ($callback) {
diff --git a/src/Eloquent/Relations/Traits/HasEagerLoading.php b/src/Eloquent/Relations/Traits/HasEagerLoading.php
index 63cddf4..aa3ff87 100644
--- a/src/Eloquent/Relations/Traits/HasEagerLoading.php
+++ b/src/Eloquent/Relations/Traits/HasEagerLoading.php
@@ -4,6 +4,10 @@
 
 use Illuminate\Database\Eloquent\Collection;
 
+/**
+ * @template TRelatedModel of \Illuminate\Database\Eloquent\Model
+ * @template TDeclaringModel of \Illuminate\Database\Eloquent\Model
+ */
 trait HasEagerLoading
 {
     /** @inheritDoc */
@@ -29,7 +33,14 @@ public function addEagerConstraints(array $models)
         }
     }
 
-    /** @inheritDoc */
+    /**
+     * Match the eagerly loaded results to their parents.
+     *
+     * @param  array<int, TDeclaringModel>  $models
+     * @param  \Illuminate\Database\Eloquent\Collection<int, TRelatedModel>  $results
+     * @param  string  $relation
+     * @return array<int, TDeclaringModel>
+     */
     public function match(array $models, Collection $results, $relation)
     {
         if ($this->customEagerMatchingCallbacks) {
diff --git a/src/Eloquent/Relations/Traits/HasExistenceQueries.php b/src/Eloquent/Relations/Traits/HasExistenceQueries.php
index 551553e..a016e03 100644
--- a/src/Eloquent/Relations/Traits/HasExistenceQueries.php
+++ b/src/Eloquent/Relations/Traits/HasExistenceQueries.php
@@ -17,6 +17,7 @@ public function getRelationExistenceQuery(Builder $query, Builder $parentQuery,
         if ($this->firstKey instanceof Closure || $this->localKey instanceof Closure) {
             $this->performJoin($query);
 
+            /** @var callable $closureKey */
             $closureKey = $this->firstKey instanceof Closure ? $this->firstKey : $this->localKey;
 
             $closureKey($query, $parentQuery);
@@ -48,8 +49,14 @@ public function getRelationExistenceQueryForSelfRelation(Builder $query, Builder
 
         $query->getModel()->setTable($hash);
 
+        $from = is_string($parentQuery->getQuery()->from)
+            ? $parentQuery->getQuery()->from
+            : (string) $parentQuery->getQuery()->from->getValue(
+                $parentQuery->getQuery()->getGrammar()
+            );
+
         return $query->select($columns)->whereColumn(
-            $parentQuery->getQuery()->from.'.'.$this->localKey,
+            "$from.$this->localKey",
             '=',
             $this->getQualifiedFirstKeyName()
         );
diff --git a/src/Eloquent/Relations/Traits/IsConcatenable.php b/src/Eloquent/Relations/Traits/IsConcatenable.php
index a592368..48bd2c7 100644
--- a/src/Eloquent/Relations/Traits/IsConcatenable.php
+++ b/src/Eloquent/Relations/Traits/IsConcatenable.php
@@ -9,13 +9,13 @@ trait IsConcatenable
     /**
      * Append the relation's through parents, foreign and local keys to a deep relationship.
      *
-     * @param list<\Illuminate\Database\Eloquent\Model> $through
-     * @param list<string|callable|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $foreignKeys
-     * @param list<string|callable|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $localKeys
+     * @param non-empty-list<string> $through
+     * @param non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $foreignKeys
+     * @param non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $localKeys
      * @param int $position
-     * @return array{0: list<string>,
-     *     1: list<string|callable|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>,
-     *     2: list<string|callable|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>}
+     * @return array{0: non-empty-list<string>,
+     *     1: non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null>,
+     *     2: non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null>}
      */
     public function appendToDeepRelationship(array $through, array $foreignKeys, array $localKeys, int $position): array
     {
diff --git a/src/Eloquent/Relations/Traits/JoinsThroughParents.php b/src/Eloquent/Relations/Traits/JoinsThroughParents.php
index 2a9579b..de79fe8 100644
--- a/src/Eloquent/Relations/Traits/JoinsThroughParents.php
+++ b/src/Eloquent/Relations/Traits/JoinsThroughParents.php
@@ -79,7 +79,7 @@ protected function throughParentJoins(Builder $query, Model $throughParent, Mode
     {
         $joins = [];
 
-        if ($localKey instanceof CompositeKey) {
+        if ($localKey instanceof CompositeKey && $foreignKey instanceof CompositeKey) {
             foreach ($localKey->columns as $i => $column) {
                 $joins[] = [$column, $foreignKey->columns[$i]];
             }
diff --git a/src/Eloquent/Relations/Traits/RetrievesIntermediateTables.php b/src/Eloquent/Relations/Traits/RetrievesIntermediateTables.php
index eea41cf..143ebff 100644
--- a/src/Eloquent/Relations/Traits/RetrievesIntermediateTables.php
+++ b/src/Eloquent/Relations/Traits/RetrievesIntermediateTables.php
@@ -11,7 +11,7 @@ trait RetrievesIntermediateTables
     /**
      * The intermediate tables to retrieve.
      *
-     * @var array<string, array{table: string, columns: list<string>, class: class-string<\Illuminate\Database\Eloquent\Model>, postProcessor: list<string>}>
+     * @var array<string, array{table: string, columns: list<string>, class: class-string<\Illuminate\Database\Eloquent\Model>, postProcessor: callable|null}>
      */
     protected $intermediateTables = [];
 
@@ -104,7 +104,10 @@ protected function hydrateIntermediateRelations(array $models)
             $prefix = $this->prefix($accessor);
 
             if (str_contains($accessor, '.')) {
-                [$path, $key] = preg_split('/\.(?=[^.]*$)/', $accessor);
+                /** @var array{0: string, 1: string} $segments */
+                $segments = preg_split('/\.(?=[^.]*$)/', $accessor);
+
+                [$path, $key] = $segments;
             } else {
                 [$path, $key] = [null, $accessor];
             }
@@ -121,7 +124,7 @@ protected function hydrateIntermediateRelations(array $models)
      * Get the intermediate relationship from the query.
      *
      * @param \Illuminate\Database\Eloquent\Model $model
-     * @param array{table: string, columns: list<string>, class: class-string<\Illuminate\Database\Eloquent\Model>, postProcessor: list<string>} $intermediateTable
+     * @param array{table: string, columns: list<string>, class: class-string<\Illuminate\Database\Eloquent\Model>, postProcessor: callable|null} $intermediateTable
      * @param string $prefix
      * @return \Illuminate\Database\Eloquent\Model
      */
@@ -185,7 +188,7 @@ protected function prefix($accessor)
     /**
      * Get the intermediate tables.
      *
-     * @return array<string, array{table: string, columns: list<string>, class: class-string<\Illuminate\Database\Eloquent\Model>, postProcessor: list<string>}>
+     * @return array<string, array{table: string, columns: list<string>, class: class-string<\Illuminate\Database\Eloquent\Model>, postProcessor: callable|null}>
      */
     public function getIntermediateTables(): array
     {
diff --git a/src/Eloquent/Relations/Traits/SupportsCompositeKeys.php b/src/Eloquent/Relations/Traits/SupportsCompositeKeys.php
index ed64108..b225098 100644
--- a/src/Eloquent/Relations/Traits/SupportsCompositeKeys.php
+++ b/src/Eloquent/Relations/Traits/SupportsCompositeKeys.php
@@ -8,6 +8,10 @@
 use Illuminate\Support\Collection as BaseCollection;
 use Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey;
 
+/**
+ * @template TRelatedModel of \Illuminate\Database\Eloquent\Model
+ * @template TDeclaringModel of \Illuminate\Database\Eloquent\Model
+ */
 trait SupportsCompositeKeys
 {
     /**
@@ -27,13 +31,19 @@ protected function hasLeadingCompositeKey(): bool
      */
     protected function addConstraintsWithCompositeKey(): void
     {
-        $columns = array_slice($this->foreignKeys[0]->columns, 1, null, true);
+        /** @var \Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey $foreignKey */
+        $foreignKey = $this->foreignKeys[0];
+
+        /** @var \Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey $localKey */
+        $localKey = $this->localKeys[0];
+
+        $columns = array_slice($foreignKey->columns, 1, null, true);
 
         foreach ($columns as $i => $column) {
             $this->query->where(
                 $this->throughParent->qualifyColumn($column),
                 '=',
-                $this->farParent[$this->localKeys[0]->columns[$i]]
+                $this->farParent[$localKey->columns[$i]]
             );
         }
     }
@@ -46,21 +56,27 @@ protected function addConstraintsWithCompositeKey(): void
      */
     protected function addEagerConstraintsWithCompositeKey(array $models): void
     {
+        /** @var \Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey $foreignKey */
+        $foreignKey = $this->foreignKeys[0];
+
+        /** @var \Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey $localKey */
+        $localKey = $this->localKeys[0];
+
         $keys = (new BaseCollection($models))->map(
-            function (Model $model) {
+            function (Model $model) use ($localKey) {
                 return array_map(
                     fn (string $column) => $model[$column],
-                    $this->localKeys[0]->columns
+                    $localKey->columns
                 );
             }
         )->values()->unique(null, true)->all();
 
         $this->query->where(
-            function (Builder $query) use ($keys) {
+            function (Builder $query) use ($foreignKey, $keys) {
                 foreach ($keys as $key) {
                     $query->orWhere(
-                        function (Builder $query) use ($key) {
-                            foreach ($this->foreignKeys[0]->columns as $i => $column) {
+                        function (Builder $query) use ($foreignKey, $key) {
+                            foreach ($foreignKey->columns as $i => $column) {
                                 $query->where(
                                     $this->throughParent->qualifyColumn($column),
                                     '=',
@@ -77,10 +93,10 @@ function (Builder $query) use ($key) {
     /**
      * Match the eagerly loaded results to their parents for a leading composite key.
      *
-     * @param list<\Illuminate\Database\Eloquent\Model> $models
-     * @param \Illuminate\Database\Eloquent\Collection<int, \Illuminate\Database\Eloquent\Model> $results
-     * @param string $relation
-     * @return list<\Illuminate\Database\Eloquent\Model>
+     * @param  array<int, TDeclaringModel>  $models
+     * @param  \Illuminate\Database\Eloquent\Collection<int, TRelatedModel>  $results
+     * @param  string  $relation
+     * @return array<int, TDeclaringModel>
      */
     protected function matchWithCompositeKey(array $models, Collection $results, string $relation): array
     {
@@ -88,8 +104,10 @@ protected function matchWithCompositeKey(array $models, Collection $results, str
 
         foreach ($models as $model) {
             $values = [];
+            /** @var \Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey $localKey */
+            $localKey = $this->localKeys[0];
 
-            foreach ($this->localKeys[0]->columns as $column) {
+            foreach ($localKey->columns as $column) {
                 $values[] = $this->getDictionaryKey(
                     $model->getAttribute($column)
                 );
@@ -118,10 +136,13 @@ protected function buildDictionaryWithCompositeKey(Collection $results): array
     {
         $dictionary = [];
 
+        /** @var \Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey $foreignKey */
+        $foreignKey = $this->foreignKeys[0];
+
         foreach ($results as $result) {
             $values = [];
 
-            foreach ($this->foreignKeys[0]->columns as $i => $column) {
+            foreach ($foreignKey->columns as $i => $column) {
                 $alias = 'laravel_through_key' . ($i > 0 ? "_$i" : '');
 
                 $values[] = $result->$alias;
@@ -142,7 +163,10 @@ protected function buildDictionaryWithCompositeKey(Collection $results): array
      */
     protected function shouldSelectWithCompositeKey(): array
     {
-        $columns = array_slice($this->foreignKeys[0]->columns, 1, null, true);
+        /** @var \Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey $foreignKey */
+        $foreignKey = $this->foreignKeys[0];
+
+        $columns = array_slice($foreignKey->columns, 1, null, true);
 
         return array_map(
             fn ($column, $i) => $this->throughParent->qualifyColumn($column) . " as laravel_through_key_$i",
@@ -159,13 +183,19 @@ protected function shouldSelectWithCompositeKey(): array
      */
     public function getRelationExistenceQueryWithCompositeKey(Builder $query): void
     {
-        $columns = array_slice($this->localKeys[0]->columns, 1, null, true);
+        /** @var \Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey $foreignKey */
+        $foreignKey = $this->foreignKeys[0];
+
+        /** @var \Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey $localKey */
+        $localKey = $this->localKeys[0];
+
+        $columns = array_slice($localKey->columns, 1, null, true);
 
         foreach ($columns as $i => $column) {
             $query->whereColumn(
                 $this->farParent->qualifyColumn($column),
                 '=',
-                $this->throughParent->qualifyColumn($this->foreignKeys[0]->columns[$i])
+                $this->throughParent->qualifyColumn($foreignKey->columns[$i])
             );
         }
     }
diff --git a/src/Eloquent/Traits/ReversesRelationships.php b/src/Eloquent/Traits/ReversesRelationships.php
index b94a985..93077a9 100644
--- a/src/Eloquent/Traits/ReversesRelationships.php
+++ b/src/Eloquent/Traits/ReversesRelationships.php
@@ -14,7 +14,7 @@ trait ReversesRelationships
      *
      * @template TRelatedModel of \Illuminate\Database\Eloquent\Model
      * @template TDeclaringModel of \Illuminate\Database\Eloquent\Model
-     * TODO
+     *
      * @param \Staudenmeir\EloquentHasManyDeep\HasManyDeep<TDeclaringModel, TRelatedModel> $relation
      * @return \Staudenmeir\EloquentHasManyDeep\HasManyDeep<TRelatedModel, $this>
      */
@@ -30,7 +30,7 @@ public function hasManyDeepFromReverse(HasManyDeep $relation): HasManyDeep
      *
      * @template TRelatedModel of \Illuminate\Database\Eloquent\Model
      * @template TDeclaringModel of \Illuminate\Database\Eloquent\Model
-     * TODO
+     *
      * @param \Staudenmeir\EloquentHasManyDeep\HasManyDeep<TDeclaringModel, TRelatedModel> $relation
      * @return \Staudenmeir\EloquentHasManyDeep\HasOneDeep<TRelatedModel, $this>
      */
@@ -46,12 +46,12 @@ public function hasOneDeepFromReverse(HasManyDeep $relation): HasOneDeep
      *
      * @template TRelatedModel of \Illuminate\Database\Eloquent\Model
      * @template TDeclaringModel of \Illuminate\Database\Eloquent\Model
-     * TODO
+     *
      * @param \Staudenmeir\EloquentHasManyDeep\HasManyDeep<TRelatedModel, TDeclaringModel> $relation
      * @return array{0: class-string<TDeclaringModel>,
      *     1: list<string>,
-     *     2: list<string|callable|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>,
-     *     3: list<string|callable|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>}
+     *     2: list<callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>,
+     *     3: list<callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>}
      */
     protected function hasOneOrManyDeepFromReverse(HasManyDeep $relation): array
     {
diff --git a/src/HasManyDeep.php b/src/HasManyDeep.php
index f959269..bdadddc 100644
--- a/src/HasManyDeep.php
+++ b/src/HasManyDeep.php
@@ -6,6 +6,7 @@
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\HasManyThrough;
+use Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey;
 use Staudenmeir\EloquentHasManyDeep\Eloquent\Relations\Traits\ExecutesQueries;
 use Staudenmeir\EloquentHasManyDeep\Eloquent\Relations\Traits\HasEagerLoading;
 use Staudenmeir\EloquentHasManyDeep\Eloquent\Relations\Traits\HasExistenceQueries;
@@ -25,32 +26,34 @@
 class HasManyDeep extends HasManyThrough implements ConcatenableRelation
 {
     use ExecutesQueries;
+    /** @use \Staudenmeir\EloquentHasManyDeep\Eloquent\Relations\Traits\HasEagerLoading<TRelatedModel, TDeclaringModel> */
     use HasEagerLoading;
     use HasExistenceQueries;
     use IsConcatenable;
     use IsCustomizable;
     use JoinsThroughParents;
     use RetrievesIntermediateTables;
+    /** @use \Staudenmeir\EloquentHasManyDeep\Eloquent\Relations\Traits\SupportsCompositeKeys<TRelatedModel, TDeclaringModel> */
     use SupportsCompositeKeys;
 
     /**
      * The "through" parent model instances.
      *
-     * @var list<\Illuminate\Database\Eloquent\Model>
+     * @var non-empty-list<\Illuminate\Database\Eloquent\Model>
      */
     protected $throughParents;
 
     /**
      * The foreign keys on the relationship.
      *
-     * @var list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>
+     * @var non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null>
      */
     protected $foreignKeys;
 
     /**
      * The local keys on the relationship.
      *
-     * @var list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>
+     * @var non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null>
      */
     protected $localKeys;
 
@@ -59,9 +62,9 @@ class HasManyDeep extends HasManyThrough implements ConcatenableRelation
      *
      * @param \Illuminate\Database\Eloquent\Builder<TRelatedModel> $query
      * @param \Illuminate\Database\Eloquent\Model $farParent
-     * @param list<\Illuminate\Database\Eloquent\Model> $throughParents
-     * @param list<string|callable|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $foreignKeys
-     * @param list<string|callable|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $localKeys
+     * @param non-empty-list<\Illuminate\Database\Eloquent\Model> $throughParents
+     * @param non-empty-list<callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $foreignKeys
+     * @param non-empty-list<callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $localKeys
      * @return void
      */
     public function __construct(Builder $query, Model $farParent, array $throughParents, array $foreignKeys, array $localKeys)
@@ -72,10 +75,11 @@ public function __construct(Builder $query, Model $farParent, array $throughPare
 
         $firstKey = is_array($foreignKeys[0])
             ? $foreignKeys[0][1]
-            : ($this->hasLeadingCompositeKey() ? $foreignKeys[0]->columns[0] : $foreignKeys[0]);
+            : ($foreignKeys[0] instanceof CompositeKey ? $foreignKeys[0]->columns[0] : $foreignKeys[0]);
 
-        $localKey = $this->hasLeadingCompositeKey() ? $localKeys[0]->columns[0] : $localKeys[0];
+        $localKey = $localKeys[0] instanceof CompositeKey ? $localKeys[0]->columns[0] : $localKeys[0];
 
+        /* @phpstan-ignore-next-line */
         parent::__construct($query, $farParent, $throughParents[0], $firstKey, $foreignKeys[1], $localKey, $localKeys[1]);
     }
 
@@ -114,7 +118,13 @@ protected function performJoin(?Builder $query = null)
         $foreignKeys = array_reverse($this->foreignKeys);
         $localKeys = array_reverse($this->localKeys);
 
-        $segments = explode(' as ', $query->getQuery()->from);
+        $from = is_string($query->getQuery()->from)
+            ? $query->getQuery()->from
+            : (string) $query->getQuery()->from->getValue(
+                $query->getQuery()->getGrammar()
+            );
+
+        $segments = explode(' as ', $from);
 
         $alias = $segments[1] ?? null;
 
@@ -182,6 +192,8 @@ public function withTrashed(...$columns)
             $columns = $columns[0];
         }
 
+        /** @var list<string> $columns */
+
         foreach ($columns as $column) {
             $this->query->withoutGlobalScope(__CLASS__ . ":$column");
         }
@@ -212,7 +224,7 @@ public function getThroughParents()
     /**
      * Get the foreign keys on the relationship.
      *
-     * @return list<string|callable|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>
+     * @return list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>
      */
     public function getForeignKeys()
     {
@@ -222,7 +234,7 @@ public function getForeignKeys()
     /**
      * Get the local keys on the relationship.
      *
-     * @return list<string|callable|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>
+     * @return list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>
      */
     public function getLocalKeys()
     {
diff --git a/src/HasOneDeep.php b/src/HasOneDeep.php
index 73df9a0..cd3ee04 100644
--- a/src/HasOneDeep.php
+++ b/src/HasOneDeep.php
@@ -16,7 +16,11 @@ class HasOneDeep extends HasManyDeep
 {
     use SupportsDefaultModels;
 
-    /** @inheritDoc */
+    /**
+     * Get the results of the relationship.
+     *
+     * @return \Illuminate\Database\Eloquent\Model|null
+     */
     public function getResults()
     {
         return $this->first() ?: $this->getDefaultFor(end($this->throughParents));
diff --git a/src/HasRelationships.php b/src/HasRelationships.php
index b003e9b..2e3cd7b 100644
--- a/src/HasRelationships.php
+++ b/src/HasRelationships.php
@@ -19,10 +19,10 @@ trait HasRelationships
      *
      * @template TRelatedModel of \Illuminate\Database\Eloquent\Model
      *
-     * @param class-string<TRelatedModel> $related TODO
+     * @param class-string<TRelatedModel> $related
      * @param list<string> $through
-     * @param list<array{0: string, 1: string}|callable|null|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $foreignKeys
-     * @param list<array{0: string, 1: string}|callable|null|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $localKeys
+     * @param list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $foreignKeys
+     * @param list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $localKeys
      * @return \Staudenmeir\EloquentHasManyDeep\HasManyDeep<TRelatedModel, $this>
      */
     public function hasManyDeep($related, array $through, array $foreignKeys = [], array $localKeys = [])
@@ -37,10 +37,10 @@ public function hasManyDeep($related, array $through, array $foreignKeys = [], a
      *
      * @template TRelatedModel of \Illuminate\Database\Eloquent\Model
      *
-     * @param class-string<TRelatedModel> $related TODO
+     * @param class-string<TRelatedModel> $related
      * @param list<string> $through
-     * @param list<array{0: string, 1: string}|callable|null|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $foreignKeys
-     * @param list<array{0: string, 1: string}|callable|null|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $localKeys
+     * @param list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $foreignKeys
+     * @param list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $localKeys
      * @return \Staudenmeir\EloquentHasManyDeep\HasOneDeep<TRelatedModel, $this>
      */
     public function hasOneDeep($related, array $through, array $foreignKeys = [], array $localKeys = [])
@@ -60,8 +60,8 @@ public function hasOneDeep($related, array $through, array $foreignKeys = [], ar
      * @return array{0: \Illuminate\Database\Eloquent\Builder<\Illuminate\Database\Eloquent\Model>,
      *     1: $this,
      *     2: list<\Illuminate\Database\Eloquent\Model>,
-     *     3: list<array{0: string, 1: string}|callable|null|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>,
-     *     4: list<array{0: string, 1: string}|callable|null|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>}
+     *     3: list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null>,
+     *     4: list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null>}
      */
     protected function hasOneOrManyDeep($related, array $through, array $foreignKeys, array $localKeys)
     {
@@ -126,7 +126,7 @@ protected function newRelatedDeepThroughInstance(string $class): Model
      *
      * @param \Illuminate\Database\Eloquent\Model $related
      * @param list<\Illuminate\Database\Eloquent\Model> $throughParents
-     * @param list<array{0: string, 1: string}|callable|null|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $foreignKeys
+     * @param list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $foreignKeys
      * @return list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>
      */
     protected function hasOneOrManyDeepForeignKeys(Model $related, array $throughParents, array $foreignKeys)
@@ -150,7 +150,7 @@ protected function hasOneOrManyDeepForeignKeys(Model $related, array $throughPar
      *
      * @param \Illuminate\Database\Eloquent\Model $related
      * @param list<\Illuminate\Database\Eloquent\Model> $throughParents
-     * @param list<array{0: string, 1: string}|callable|null|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $localKeys
+     * @param list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $localKeys
      * @return list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey>
      */
     protected function hasOneOrManyDeepLocalKeys(Model $related, array $throughParents, array $localKeys)
@@ -177,9 +177,9 @@ protected function hasOneOrManyDeepLocalKeys(Model $related, array $throughParen
      *
      * @param \Illuminate\Database\Eloquent\Builder<TRelatedModel> $query
      * @param TDeclaringModel $farParent
-     * @param list<\Illuminate\Database\Eloquent\Model> $throughParents
-     * @param list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $foreignKeys
-     * @param list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $localKeys
+     * @param non-empty-list<\Illuminate\Database\Eloquent\Model> $throughParents
+     * @param non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $foreignKeys
+     * @param non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $localKeys
      * @return \Staudenmeir\EloquentHasManyDeep\HasManyDeep<TRelatedModel, TDeclaringModel>
      */
     protected function newHasManyDeep(Builder $query, Model $farParent, array $throughParents, array $foreignKeys, array $localKeys)
@@ -195,9 +195,9 @@ protected function newHasManyDeep(Builder $query, Model $farParent, array $throu
      *
      * @param \Illuminate\Database\Eloquent\Builder<TRelatedModel> $query
      * @param TDeclaringModel $farParent
-     * @param list<\Illuminate\Database\Eloquent\Model> $throughParents
-     * @param list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $foreignKeys
-     * @param list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey> $localKeys
+     * @param non-empty-list<\Illuminate\Database\Eloquent\Model> $throughParents
+     * @param non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $foreignKeys
+     * @param non-empty-list<array{0: string, 1: string}|callable|string|\Staudenmeir\EloquentHasManyDeep\Eloquent\CompositeKey|null> $localKeys
      * @return \Staudenmeir\EloquentHasManyDeep\HasOneDeep<TRelatedModel, TDeclaringModel>
      */
     protected function newHasOneDeep(Builder $query, Model $farParent, array $throughParents, array $foreignKeys, array $localKeys)