diff --git a/phpstan.neon b/phpstan.neon
index f4476cb..3090d32 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,4 +1,4 @@
 parameters:
-  level: 5
+  level: 6
   paths:
   - %currentWorkingDirectory%/src/
diff --git a/src/Command/Add/AddFiles.php b/src/Command/Add/AddFiles.php
index 394bf5d..abc1002 100644
--- a/src/Command/Add/AddFiles.php
+++ b/src/Command/Add/AddFiles.php
@@ -150,7 +150,7 @@ public function intentToAdd(bool $bool = true): AddFiles
      * `dir/file1` modified in the working tree, a file `dir/file2` added to the
      * working tree, but also a file `dir/file3` removed from the working tree).
      *
-     * @param array $files
+     * @param array<string> $files
      *
      * @return \SebastianFeldmann\Git\Command\Add\AddFiles
      */
diff --git a/src/Command/Base.php b/src/Command/Base.php
index a0a259b..91dc1ba 100644
--- a/src/Command/Base.php
+++ b/src/Command/Base.php
@@ -65,7 +65,7 @@ public function getCommand(): string
     /**
      * Return list of acceptable exit codes.
      *
-     * @return array
+     * @return array<int>
      */
     public function getAcceptableExitCodes(): array
     {
diff --git a/src/Command/Checkout/RestoreWorkingTree.php b/src/Command/Checkout/RestoreWorkingTree.php
index d27b1ae..e0724c8 100644
--- a/src/Command/Checkout/RestoreWorkingTree.php
+++ b/src/Command/Checkout/RestoreWorkingTree.php
@@ -24,16 +24,16 @@
 class RestoreWorkingTree extends Base
 {
     /**
-     * Files and directories to restore.
+     * Files and directories to restore
      *
-     * @var string[]
+     * @var array<string>
      */
     private $files = ['.'];
 
     /**
-     * Limits the paths affected by the operation to those specified here.
+     * Limits the paths affected by the operation to those specified here
      *
-     * @param array $files
+     * @param array<string> $files
      *
      * @return \SebastianFeldmann\Git\Command\Checkout\RestoreWorkingTree
      */
@@ -44,7 +44,7 @@ public function files(array $files): RestoreWorkingTree
     }
 
     /**
-     * Return the command to execute.
+     * Return the command to execute
      *
      * @return string
      */
diff --git a/src/Command/Config/ListSettings/MapSettings.php b/src/Command/Config/ListSettings/MapSettings.php
index 2af9357..fcc8919 100644
--- a/src/Command/Config/ListSettings/MapSettings.php
+++ b/src/Command/Config/ListSettings/MapSettings.php
@@ -24,10 +24,10 @@
 class MapSettings implements OutputFormatter
 {
     /**
-     * Format the output.
+     * Format the output
      *
-     * @param  array $output
-     * @return iterable
+     * @param  array<string> $output
+     * @return iterable<string, string>
      */
     public function format(array $output): iterable
     {
diff --git a/src/Command/Diff/Compare/FullDiffList.php b/src/Command/Diff/Compare/FullDiffList.php
index f5e9ca7..105a407 100644
--- a/src/Command/Diff/Compare/FullDiffList.php
+++ b/src/Command/Diff/Compare/FullDiffList.php
@@ -29,7 +29,7 @@
 class FullDiffList implements OutputFormatter
 {
     /**
-     * Available line types of git diff output.
+     * Available line types of git diff output
      */
     private const LINE_TYPE_START      = 'Start';
     private const LINE_TYPE_HEADER     = 'Header';
@@ -41,11 +41,11 @@ class FullDiffList implements OutputFormatter
     private const LINE_TYPE_CODE       = 'ChangeCode';
 
     /**
-     * Search and parse strategy.
+     * Search and parse strategy
      *
      * Define possible follow up lines for each line type to minimize search effort.
      *
-     * @var array
+     * @var array<string, array<string>>
      */
     private static $lineTypesToCheck = [
         self::LINE_TYPE_START => [
@@ -82,9 +82,9 @@ class FullDiffList implements OutputFormatter
     ];
 
     /**
-     * Maps git diff output to file operations.
+     * Maps git diff output to file operations
      *
-     * @var array
+     * @var array<string, string>
      */
     private static $opsMap = [
         'old'     => File::OP_MODIFIED,
@@ -95,52 +95,52 @@ class FullDiffList implements OutputFormatter
     ];
 
     /**
-     * List of diff File objects.
+     * List of diff File objects
      *
-     * @var \SebastianFeldmann\Git\Diff\File[]
+     * @var array<\SebastianFeldmann\Git\Diff\File>
      */
     private $files = [];
 
     /**
-     * The currently processed file.
+     * The currently processed file
      *
      * @var \SebastianFeldmann\Git\Diff\File
      */
     private $currentFile;
 
     /**
-     * The file name of the currently processed file.
+     * The file name of the currently processed file
      *
      * @var string
      */
     private $currentFileName;
 
     /**
-     * The change position of the currently processed file.
+     * The change position of the currently processed file
      *
      * @var string
      */
     private $currentPosition;
 
     /**
-     * The operation of the currently processed file.
+     * The operation of the currently processed file
      *
      * @var string
      */
     private $currentOperation;
 
     /**
-     * List of collected changes.
+     * List of collected changes
      *
      * @var \SebastianFeldmann\Git\Diff\Change[]
      */
     private $currentChanges = [];
 
     /**
-     * Format the output.
+     * Format the output
      *
-     * @param  array $output
-     * @return iterable
+     * @param  array<string> $output
+     * @return iterable<\SebastianFeldmann\Git\Diff\File>
      */
     public function format(array $output): iterable
     {
@@ -166,7 +166,7 @@ public function format(array $output): iterable
     }
 
     /**
-     * Is the given line a diff header line.
+     * Is the given line a diff header line
      *
      * diff --git a/some/file b/some/file
      *
@@ -176,7 +176,7 @@ public function format(array $output): iterable
     private function isHeaderLine(string $line): bool
     {
         $matches = [];
-        if (preg_match('#^diff --git [a|b|c|i|w|o]/(.*) [a|b|c|i|w|o]/(.*)#', $line, $matches)) {
+        if (preg_match('#^diff --git [abciwo]/(.*) [abciwo]/(.*)#', $line, $matches)) {
             $this->appendCollectedFileAndChanges();
             $this->currentOperation = File::OP_MODIFIED;
             $this->currentFileName  = $matches[2];
@@ -250,7 +250,7 @@ private function isHeaderIndexLine(string $line): bool
     private function isHeaderFormatLine(string $line): bool
     {
         $matches = [];
-        return (bool)preg_match('#^[\-\+]{3} [a|b|c|i|w|o]?/.*#', $line, $matches);
+        return (bool)preg_match('#^[\\-\\+]{3} [abciwo]?/.*#', $line, $matches);
     }
 
     /**
diff --git a/src/Command/DiffIndex/GetStagedFiles/FilterByStatus.php b/src/Command/DiffIndex/GetStagedFiles/FilterByStatus.php
index 9c7a958..17dd962 100644
--- a/src/Command/DiffIndex/GetStagedFiles/FilterByStatus.php
+++ b/src/Command/DiffIndex/GetStagedFiles/FilterByStatus.php
@@ -24,16 +24,16 @@
 class FilterByStatus implements OutputFormatter
 {
     /**
-     * List of status to keep.
+     * List of status to keep
      *
-     * @var array
+     * @var array<string>
      */
     private $status;
 
     /**
-     * FilterByStatus constructor.
+     * FilterByStatus constructor
      *
-     * @param array $status
+     * @param array<string> $status
      */
     public function __construct(array $status)
     {
@@ -41,10 +41,10 @@ public function __construct(array $status)
     }
 
     /**
-     * Format the output.
+     * Format the output
      *
-     * @param  array $output
-     * @return iterable
+     * @param  array<string> $output
+     * @return iterable<string>
      */
     public function format(array $output): iterable
     {
diff --git a/src/Command/DiffIndex/GetUnstagedPatch.php b/src/Command/DiffIndex/GetUnstagedPatch.php
index c6d30ca..29c7944 100644
--- a/src/Command/DiffIndex/GetUnstagedPatch.php
+++ b/src/Command/DiffIndex/GetUnstagedPatch.php
@@ -34,7 +34,7 @@ class GetUnstagedPatch extends Base
     /**
      * Return list of acceptable exit codes.
      *
-     * @return array
+     * @return array<int>
      */
     public function getAcceptableExitCodes(): array
     {
diff --git a/src/Command/Log/Commits/Jsonized.php b/src/Command/Log/Commits/Jsonized.php
index d955561..064c1c4 100644
--- a/src/Command/Log/Commits/Jsonized.php
+++ b/src/Command/Log/Commits/Jsonized.php
@@ -34,8 +34,8 @@ class Jsonized implements OutputFormatter
     /**
      * Format the output.
      *
-     * @param  array $output
-     * @return iterable
+     * @param  array<string> $output
+     * @return iterable<Commit>
      * @throws \Exception
      */
     public function format(array $output): iterable
diff --git a/src/Command/Rm/RemoveFiles.php b/src/Command/Rm/RemoveFiles.php
index 6249fb0..db3183a 100644
--- a/src/Command/Rm/RemoveFiles.php
+++ b/src/Command/Rm/RemoveFiles.php
@@ -107,8 +107,7 @@ public function recursive(bool $bool = true): RemoveFiles
      * `git rm 'd*'` and `git rm 'd/*'`, as the former will also remove all of
      * directory `d2`.
      *
-     * @param array $files
-     *
+     * @param  array<string> $files
      * @return \SebastianFeldmann\Git\Command\Rm\RemoveFiles
      */
     public function files(array $files): RemoveFiles
diff --git a/src/Command/Status/Porcelain/PathList.php b/src/Command/Status/Porcelain/PathList.php
index db68f18..f51e609 100644
--- a/src/Command/Status/Porcelain/PathList.php
+++ b/src/Command/Status/Porcelain/PathList.php
@@ -25,15 +25,15 @@
 class PathList implements OutputFormatter
 {
     /**
-     * Nul-byte used as a separator in `--porcelain=v1 -z` output.
+     * Nul-byte used as a separator in `--porcelain=v1 -z` output
      */
     private const NUL_BYTE = "\x00";
 
     /**
-     * Format the output.
+     * Format the output
      *
-     * @param array $output
-     * @return iterable
+     * @param  array<string> $output
+     * @return iterable<Path>
      */
     public function format(array $output): iterable
     {
@@ -52,13 +52,13 @@ public function format(array $output): iterable
     }
 
     /**
-     * Parse the status line and return a 3-tuple of path parts.
+     * Parse the status line and return a 3-tuple of path parts
      *
      * - 0: status code
      * - 1: path
      * - 2: original path, if renamed or copied
      *
-     * @return array<int, array<string, string, mixed>>
+     * @return array<int, array<int, string|null>>
      */
     private function parseStatusLine(string $statusLine): array
     {
@@ -83,10 +83,10 @@ private function parseStatusLine(string $statusLine): array
     }
 
     /**
-     * Split the status line on the nul-byte.
+     * Split the status line on the nul-byte
      *
-     * @param string $statusLine
-     * @return array
+     * @param  string $statusLine
+     * @return array<string>
      */
     private function splitOnNulByte(string $statusLine): array
     {
diff --git a/src/CommitMessage.php b/src/CommitMessage.php
index 0ba7a30..965c3ce 100644
--- a/src/CommitMessage.php
+++ b/src/CommitMessage.php
@@ -139,7 +139,7 @@ public function getRawContent(): string
      *
      * This includes lines that are comments.
      *
-     * @return array
+     * @return array<string>
      */
     public function getLines(): array
     {
@@ -215,7 +215,7 @@ public function getBody(): string
     /**
      * Return lines from line nr. 3 to the last line
      *
-     * @return array
+     * @return array<string>
      */
     public function getBodyLines(): array
     {
@@ -237,9 +237,9 @@ public function getCommentCharacter(): string
     /**
      * Get the lines that are not comments
      *
-     * @param  array  $rawLines
-     * @param  string $commentCharacter
-     * @return string[]
+     * @param  array<string> $rawLines
+     * @param  string        $commentCharacter
+     * @return array<string>
      */
     private function getContentLines(array $rawLines, string $commentCharacter): array
     {
diff --git a/src/Diff/Change.php b/src/Diff/Change.php
index 5e8c115..fcb2f9b 100644
--- a/src/Diff/Change.php
+++ b/src/Diff/Change.php
@@ -62,7 +62,7 @@ public function __construct(string $ranges, string $header = '')
     }
 
     /**
-     * Header getter.
+     * Header getter
      *
      * @return string
      */
@@ -72,9 +72,9 @@ public function getHeader(): string
     }
 
     /**
-     * Pre range getter.
+     * Pre range getter
      *
-     * @return array
+     * @return array<string, int|null>
      */
     public function getPre(): array
     {
@@ -82,9 +82,9 @@ public function getPre(): array
     }
 
     /**
-     * Post range getter.
+     * Post range getter
      *
-     * @return array
+     * @return array<string, int|null>
      */
     public function getPost(): array
     {
@@ -92,7 +92,7 @@ public function getPost(): array
     }
 
     /**
-     * Return list of changed lines.
+     * Return list of changed lines
      *
      * @return \SebastianFeldmann\Git\Diff\Line[]
      */
@@ -118,7 +118,7 @@ public function getAddedContent(): array
     }
 
     /**
-     * Add a line to the change.
+     * Add a line to the change
      *
      * @param  \SebastianFeldmann\Git\Diff\Line $line
      * @return void
@@ -129,7 +129,7 @@ public function addLine(Line $line): void
     }
 
     /**
-     * Parse ranges and split them into pre and post range.
+     * Parse ranges and split them into pre and post range
      *
      * @param  string $ranges
      * @return void
@@ -153,12 +153,12 @@ function ($value) {
 
         $this->pre = [
             'from' => isset($matches[1]) ? (int) $matches[1] : null,
-            'to' => isset($matches[2]) ? (int) $matches[2] : null,
+            'to'   => isset($matches[2]) ? (int) $matches[2] : null,
         ];
 
         $this->post = [
             'from' => isset($matches[3]) ? (int) $matches[3] : null,
-            'to' => isset($matches[4]) ? (int) $matches[4] : null,
+            'to'   => isset($matches[4]) ? (int) $matches[4] : null,
         ];
     }
 }
diff --git a/src/Diff/Line.php b/src/Diff/Line.php
index 59005cb..f2c94f8 100644
--- a/src/Diff/Line.php
+++ b/src/Diff/Line.php
@@ -29,7 +29,7 @@ class Line
 
     /**
      * Map diff output to file operation
-     * @var array
+     * @var array<string, string>
      */
     public static $opsMap = [
         '+' => self::ADDED,
diff --git a/src/Log/Commit.php b/src/Log/Commit.php
index 1bcc96b..e52b1d1 100644
--- a/src/Log/Commit.php
+++ b/src/Log/Commit.php
@@ -27,7 +27,7 @@ class Commit
     private $hash;
 
     /**
-     * @var array
+     * @var array<string>
      */
     private $names;
 
@@ -52,10 +52,10 @@ class Commit
     private $author;
 
     /**
-     * Commit constructor.
+     * Commit constructor
      *
      * @param string             $hash
-     * @param array              $names
+     * @param array<string>      $names
      * @param string             $subject
      * @param string             $body
      * @param \DateTimeImmutable $date
@@ -78,7 +78,7 @@ public function __construct(
     }
 
     /**
-     * Hash getter.
+     * Hash getter
      *
      * @return string
      */
@@ -88,7 +88,7 @@ public function getHash(): string
     }
 
     /**
-     * Does the commit have names.
+     * Does the commit have names
      *
      * @return bool
      */
@@ -98,9 +98,9 @@ public function hasNames(): bool
     }
 
     /**
-     * Names getter.
+     * Names getter
      *
-     * @return array
+     * @return array<string>
      */
     public function getNames(): array
     {
@@ -108,7 +108,7 @@ public function getNames(): array
     }
 
     /**
-     * Description getter.
+     * Description getter
      *
      * @deprecated
      *
@@ -120,7 +120,7 @@ public function getDescription(): string
     }
 
     /**
-     * Subject getter.
+     * Subject getter
      *
      * @return string
      */
@@ -130,7 +130,7 @@ public function getSubject(): string
     }
 
     /**
-     * Body getter.
+     * Body getter
      *
      * @return string
      */
@@ -140,7 +140,7 @@ public function getBody(): string
     }
 
     /**
-     * Date getter.
+     * Date getter
      *
      * @return \DateTimeImmutable
      */
@@ -150,7 +150,7 @@ public function getDate(): \DateTimeImmutable
     }
 
     /**
-     * Author getter.
+     * Author getter
      *
      * @return string
      */
diff --git a/src/Operator/Config.php b/src/Operator/Config.php
index b44465b..58138ae 100644
--- a/src/Operator/Config.php
+++ b/src/Operator/Config.php
@@ -76,7 +76,7 @@ public function getSafely(string $name, string $default = '')
      *
      * For example: ['color.branch' => 'auto', 'color.diff' => 'auto]
      *
-     * @return array
+     * @return array<string, string>
      */
     public function getSettings(): array
     {
diff --git a/src/Operator/Index.php b/src/Operator/Index.php
index 41280c0..b06903a 100644
--- a/src/Operator/Index.php
+++ b/src/Operator/Index.php
@@ -53,7 +53,7 @@ class Index extends Base
      * Get the list of files that changed
      *
      * @param  array<string> $diffFilter List of status you want to get returned, choose from [A,C,D,M,R,T,U,X,B,*]
-     * @return array
+     * @return array<string>
      */
     public function getStagedFiles(array $diffFilter = []): array
     {
@@ -125,8 +125,8 @@ public function updateIndex(array $files): bool
      * If `$ignoreRemoval` is `true`, files removed in the working tree are
      * ignored and not removed from the index.
      *
-     * @param  array $files
-     * @param  bool  $ignoreRemoval Ignore files that have been removed from the working tree
+     * @param  array<string> $files
+     * @param  bool          $ignoreRemoval Ignore files that have been removed from the working tree
      * @return bool
      */
     public function updateIndexToMatchWorkingTree(array $files, bool $ignoreRemoval = false): bool
@@ -148,7 +148,7 @@ public function updateIndexToMatchWorkingTree(array $files, bool $ignoreRemoval
      *
      * An entry for the path is placed in the index with no content.
      *
-     * @param array $files
+     * @param  array<string> $files
      * @return bool
      */
     public function recordIntentToAddFiles(array $files): bool
@@ -162,10 +162,10 @@ public function recordIntentToAddFiles(array $files): bool
     /**
      * Remove files from the working tree and from the index
      *
-     * @param  array $files     The files to remove.
-     * @param  bool $recursive  Allow recursive removal when a leading directory name is given
-     * @param  bool $cachedOnly Unstage and remove paths only from the index.
-     *                          The working tree is untouched.
+     * @param  array<string> $files      The files to remove.
+     * @param  bool          $recursive  Allow recursive removal when a leading directory name is given
+     * @param  bool          $cachedOnly Unstage and remove paths only from the index.
+     *                                   The working tree is untouched.
      * @return bool
      */
     public function removeFiles(
@@ -234,17 +234,20 @@ private function cacheFiles(array $diffFilter, array $files): void
     /**
      * Retrieve files from cache
      *
-     * @param  array $diffFilter
-     * @return array
+     * @param  array<string> $diffFilter
+     * @return array<string>
      */
     private function retrieveFromCache(array $diffFilter): array
     {
-        print_r($this->files);
         return $this->files[implode($diffFilter)];
     }
 
     /**
      * Sort files by file suffix
+     *
+     * @param  string        $suffix
+     * @param  array<string> $diffFilter
+     * @return array<string>
      */
     private function retrieveStagedFilesByType(string $suffix, array $diffFilter): array
     {
diff --git a/src/Repository.php b/src/Repository.php
index b64054f..8705eba 100644
--- a/src/Repository.php
+++ b/src/Repository.php
@@ -55,7 +55,7 @@ class Repository
     /**
      * Map of operators
      *
-     * @var array
+     * @var array<string, object>
      */
     private $operator = [];
 
diff --git a/src/Url.php b/src/Url.php
index d6644fb..dbdd5e1 100644
--- a/src/Url.php
+++ b/src/Url.php
@@ -145,7 +145,7 @@ public function getRepoName(): string
      * Detect the url components
      *
      * @param  string $url
-     * @return array
+     * @return array<string, int|string>
      */
     private function parseUrl(string $url): array
     {