diff --git a/Algorithm/PathFinding/AStar.php b/Algorithm/PathFinding/AStar.php
index e5aa81b61..3c990b2c2 100644
--- a/Algorithm/PathFinding/AStar.php
+++ b/Algorithm/PathFinding/AStar.php
@@ -63,6 +63,7 @@ final class AStar implements PathFinderInterface
                 break;
             }
 
+            /** @var AStarNode[] $neighbors */
             $neighbors       = $grid->getNeighbors($node, $movement);
             $neighborsLength = \count($neighbors);
             for ($i = 0; $i < $neighborsLength; ++$i) {
diff --git a/Algorithm/PathFinding/Grid.php b/Algorithm/PathFinding/Grid.php
index 99901f8d9..dae9861b0 100644
--- a/Algorithm/PathFinding/Grid.php
+++ b/Algorithm/PathFinding/Grid.php
@@ -175,6 +175,7 @@ class Grid
         }
 
         if ($movement === MovementType::STRAIGHT) {
+            /** @var Node[] $neighbors */
             return $neighbors;
         }
 
@@ -211,6 +212,7 @@ class Grid
             $neighbors[] = $this->getNode($x - 1, $y + 1);
         }
 
+        /** @var Node[] $neighbors */
         return $neighbors;
     }
 }
diff --git a/Algorithm/PathFinding/JumpPointSearch.php b/Algorithm/PathFinding/JumpPointSearch.php
index 7e7eba3be..3a45b0922 100644
--- a/Algorithm/PathFinding/JumpPointSearch.php
+++ b/Algorithm/PathFinding/JumpPointSearch.php
@@ -92,6 +92,7 @@ final class JumpPointSearch implements PathFinderInterface
      */
     public static function identifySuccessors(JumpPointNode $node, Grid $grid, int $heuristic, int $movement, JumpPointNode $endNode, Heap $openList) : Heap
     {
+        /** @var JumpPointNode[] $neighbors */
         $neighbors       = self::findNeighbors($node, $movement, $grid);
         $neighborsLength = \count($neighbors);
 
@@ -207,6 +208,7 @@ final class JumpPointSearch implements PathFinderInterface
             }
         }
 
+        /** @var JumpPointNode[] $neighbors */
         return $neighbors;
     }
 
@@ -284,6 +286,7 @@ final class JumpPointSearch implements PathFinderInterface
             }
         }
 
+        /** @var JumpPointNode[] $neighbors */
         return $neighbors;
     }
 
@@ -357,6 +360,7 @@ final class JumpPointSearch implements PathFinderInterface
             }
         }
 
+        /** @var JumpPointNode[] $neighbors */
         return $neighbors;
     }
 
@@ -448,6 +452,7 @@ final class JumpPointSearch implements PathFinderInterface
             }
         }
 
+        /** @var JumpPointNode[] $neighbors */
         return $neighbors;
     }
 
diff --git a/Math/Parser/Evaluator.php b/Math/Parser/Evaluator.php
index df3c06b6d..4544ad6f1 100644
--- a/Math/Parser/Evaluator.php
+++ b/Math/Parser/Evaluator.php
@@ -29,7 +29,7 @@ final class Evaluator
      *
      * @param string $equation Formula to evaluate
      *
-     * @return float
+     * @return null|float
      *
      * @throws \Exception
      *
diff --git a/Math/Statistic/Forecast/Error.php b/Math/Statistic/Forecast/Error.php
index f5d605b52..0ef885653 100644
--- a/Math/Statistic/Forecast/Error.php
+++ b/Math/Statistic/Forecast/Error.php
@@ -326,7 +326,7 @@ final class Error
         $deviation = MeasureOfDispersion::meanDeviation($observed);
 
         foreach ($errors as $error) {
-            $error[] = $error / $deviation;
+            $scaled[] = $error / $deviation;
         }
 
         return $scaled;
diff --git a/Math/Topology/Metrics2D.php b/Math/Topology/Metrics2D.php
index 5622d6b5a..92ecc7d1e 100644
--- a/Math/Topology/Metrics2D.php
+++ b/Math/Topology/Metrics2D.php
@@ -196,8 +196,8 @@ final class Metrics2D
      *
      * @latex d(p, q) = \sum_{n=1}^N{|p_i - q_i|}
      *
-     * @param array<string, int|float> $a 2-D array with x and y coordinate
-     * @param array<string, int|float> $b 2-D array with x and y coordinate
+     * @param array<int, int|float> $a 2-D array with x and y coordinate
+     * @param array<int, int|float> $b 2-D array with x and y coordinate
      *
      * @return int
      *
@@ -226,8 +226,8 @@ final class Metrics2D
      *
      * In order to use this with objects the objects would have to implement some kind of value representation for comparison.
      *
-     * @param array<string, int|float> $a Array with elements
-     * @param array<string, int|float> $b Array with same elements but different order
+     * @param array<int, int|float> $a Array with elements
+     * @param array<int, int|float> $b Array with same elements but different order
      *
      * @return int
      *