diff --git a/CHANGELOG.md b/CHANGELOG.md
index 049eca31..e80fb1d4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,7 @@
 
 ## 2.0.1 under development
 
-- no changes in this release.
+- Bug #84: Change the type of the `$level` parameter in the `Message` constructor to `string` (dood-)
 
 ## 2.0.0 May 22, 2022
 
diff --git a/psalm.xml b/psalm.xml
index 4fa75818..deb39dc1 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
 <psalm
-    errorLevel="2"
+    errorLevel="1"
     resolveFromConfigFile="true"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="https://getpsalm.org/schema/config"
diff --git a/src/Logger.php b/src/Logger.php
index 2e058f45..a1b48575 100644
--- a/src/Logger.php
+++ b/src/Logger.php
@@ -35,6 +35,9 @@
  *
  * When the application ends or {@see Logger::$flushInterval} is reached, Logger will call {@see Logger::flush()}
  * to send logged messages to different log targets, such as file or email according to the {@see Logger::$targets}.
+ *
+ * @psalm-import-type Backtrace from Message
+ * @psalm-import-type LogMessageContext from Message
  */
 final class Logger implements LoggerInterface
 {
@@ -143,6 +146,15 @@ public function getTargets(): array
         return $this->targets;
     }
 
+    /**
+     * @param string $level
+     * @param string|Stringable $message
+     * @param array $context
+     * @psalm-param LogMessageContext $context
+     * @psalm-suppress MoreSpecificImplementedParamType
+     *
+     * @return void
+     */
     public function log(mixed $level, string|Stringable $message, array $context = []): void
     {
         $context['time'] ??= microtime(true);
@@ -205,7 +217,7 @@ public function setTraceLevel(int $traceLevel): self
     /**
      * Sets an array of paths to exclude from tracing when tracing is enabled with {@see Logger::setTraceLevel()}.
      *
-     * @param array $excludedTracePaths The paths to exclude from tracing.
+     * @param string[] $excludedTracePaths The paths to exclude from tracing.
      *
      * @throws InvalidArgumentException for non-string values.
      *
@@ -216,6 +228,7 @@ public function setTraceLevel(int $traceLevel): self
     public function setExcludedTracePaths(array $excludedTracePaths): self
     {
         foreach ($excludedTracePaths as $excludedTracePath) {
+            /** @psalm-suppress DocblockTypeContradiction */
             if (!is_string($excludedTracePath)) {
                 throw new InvalidArgumentException(sprintf(
                     'The trace path must be a string, %s received.',
@@ -231,7 +244,7 @@ public function setExcludedTracePaths(array $excludedTracePaths): self
     /**
      * Sets a target to {@see Logger::$targets}.
      *
-     * @param array $targets The log targets. Each array element represents a single {@see \Yiisoft\Log\Target}
+     * @param Target[] $targets The log targets. Each array element represents a single {@see \Yiisoft\Log\Target}
      * instance or the configuration for creating the log target instance.
      *
      * @throws InvalidArgumentException for non-instance Target.
@@ -281,8 +294,10 @@ private function dispatch(array $messages, bool $final): void
      * Collects a trace when tracing is enabled with {@see Logger::setTraceLevel()}.
      *
      * @param array $backtrace The list of call stack information.
+     * @psalm-param Backtrace|list<array{object?:object,args?:array}> $backtrace
      *
      * @return array Collected a list of call stack information.
+     * @psalm-return Backtrace
      */
     private function collectTrace(array $backtrace): array
     {
diff --git a/src/Message.php b/src/Message.php
index 19212699..d1e49bd3 100644
--- a/src/Message.php
+++ b/src/Message.php
@@ -13,6 +13,20 @@
 
 /**
  * Message is a data object that stores log message data.
+ *
+ * @psalm-type Backtrace = list<array{
+ *     file:string,
+ *     line:int,
+ *     function?:string,
+ *     class?:string,
+ *     type?:string,
+ * }>
+ * @psalm-type LogMessageContext = array{
+ *     category?:string,
+ *     memory?:int,
+ *     time?:float,
+ *     trace?:Backtrace,
+ * }&array
  */
 final class Message
 {
@@ -29,7 +43,8 @@ final class Message
     private string $message;
 
     /**
-     * @var array Log message context.
+     * @var array<string, mixed> Log message context.
+     * @psalm-var LogMessageContext
      *
      * Message context has a following keys:
      *
@@ -41,16 +56,17 @@ final class Message
     private array $context;
 
     /**
-     * @param mixed $level Log message level.
+     * @param string $level Log message level.
      * @param string|Stringable $message Log message.
-     * @param array $context Log message context.
+     * @param array<string, mixed> $context Log message context.
+     * @psalm-param LogMessageContext $context
      *
      * @throws InvalidArgumentException for invalid log message level.
      *
      * @see LoggerTrait::log()
      * @see LogLevel
      */
-    public function __construct(mixed $level, string|Stringable $message, array $context = [])
+    public function __construct(string $level, string|Stringable $message, array $context = [])
     {
         $this->level = Logger::validateLevel($level);
         $this->message = $this->parse($message, $context);
@@ -86,6 +102,7 @@ public function message(): string
      * @param mixed $default If the context parameter does not exist, the `$default` will be returned.
      *
      * @return mixed The context parameter value.
+     * @psalm-return LogMessageContext|mixed
      */
     public function context(string $name = null, mixed $default = null): mixed
     {
@@ -101,7 +118,8 @@ public function context(string $name = null, mixed $default = null): mixed
      * where foo will be replaced by the context data in key "foo".
      *
      * @param string|Stringable $message Raw log message.
-     * @param array $context Message context.
+     * @param array<string, mixed> $context Message context.
+     * @psalm-param LogMessageContext $context
      *
      * @return string Parsed message.
      */
@@ -113,6 +131,7 @@ private function parse(string|Stringable $message, array $context): string
             $placeholderName = $matches[1];
 
             if (isset($context[$placeholderName])) {
+                /** @psalm-suppress PossiblyInvalidCast */
                 return (string) $context[$placeholderName];
             }
 
diff --git a/src/Message/Formatter.php b/src/Message/Formatter.php
index fb34f27c..bc7d337d 100644
--- a/src/Message/Formatter.php
+++ b/src/Message/Formatter.php
@@ -21,6 +21,8 @@
  * Formatter formats log messages.
  *
  * @internal
+ *
+ * @psalm-import-type Backtrace from Message
  */
 final class Formatter
 {
@@ -125,6 +127,7 @@ private function defaultFormat(Message $message, array $commonContext): string
         $time = $this->getTime($message);
         $prefix = $this->getPrefix($message, $commonContext);
         $context = $this->getContext($message, $commonContext);
+        /** @var string $category */
         $category = $message->context('category', CategoryFilter::DEFAULT);
 
         return "{$time} {$prefix}[{$message->level()}][{$category}] {$message->message()}{$context}";
@@ -139,6 +142,7 @@ private function defaultFormat(Message $message, array $commonContext): string
      */
     private function getTime(Message $message): string
     {
+        /** @psalm-suppress PossiblyInvalidCast */
         $timestamp = (string) $message->context('time', microtime(true));
 
         $format = match (true) {
@@ -199,12 +203,19 @@ private function getContext(Message $message, array $commonContext): string
             $context[] = $trace;
         }
 
+        /**
+         * @var array-key $name
+         * @var mixed $value
+         */
         foreach ($message->context() as $name => $value) {
             if ($name !== 'trace') {
                 $context[] = "{$name}: " . $this->convertToString($value);
             }
         }
 
+        /**
+         * @var mixed $value
+         */
         foreach ($commonContext as $name => $value) {
             $common[] = "{$name}: " . $this->convertToString($value);
         }
@@ -222,7 +233,8 @@ private function getContext(Message $message, array $commonContext): string
      */
     private function getTrace(Message $message): string
     {
-        $traces = (array) $message->context('trace', []);
+        /** @psalm-var Backtrace $traces */
+        $traces = $message->context('trace', []);
 
         foreach ($traces as $key => $trace) {
             if (isset($trace['file'], $trace['line'])) {
@@ -230,6 +242,7 @@ private function getTrace(Message $message): string
             }
         }
 
+        /** @var string[] $traces */
         return empty($traces) ? '' : "trace:\n    " . implode("\n    ", $traces);
     }
 
@@ -243,7 +256,7 @@ private function getTrace(Message $message): string
     private function convertToString(mixed $value): string
     {
         if (is_object($value) && method_exists($value, '__toString')) {
-            return $value->__toString();
+            return (string) $value;
         }
 
         return VarDumper::create($value)->asString();
diff --git a/src/PsrTarget.php b/src/PsrTarget.php
index 7bc07843..58dcc36f 100644
--- a/src/PsrTarget.php
+++ b/src/PsrTarget.php
@@ -38,7 +38,9 @@ public function getLogger(): LoggerInterface
     protected function export(): void
     {
         foreach ($this->getMessages() as $message) {
-            $this->logger->log($message->level(), $message->message(), $message->context());
+            /** @var array $context */
+            $context = $message->context();
+            $this->logger->log($message->level(), $message->message(), $context);
         }
     }
 }
diff --git a/src/Target.php b/src/Target.php
index 1be188b3..b64ff265 100644
--- a/src/Target.php
+++ b/src/Target.php
@@ -115,7 +115,7 @@ public function collect(array $messages, bool $final): void
     /**
      * Sets a list of log message categories that this target is interested in.
      *
-     * @param array $categories The list of log message categories.
+     * @param string[] $categories The list of log message categories.
      *
      * @throws InvalidArgumentException for invalid log message categories structure.
      *
@@ -132,7 +132,7 @@ public function setCategories(array $categories): self
     /**
      * Sets a list of log message categories that this target is NOT interested in.
      *
-     * @param array $except The list of log message categories.
+     * @param string[] $except The list of log message categories.
      *
      * @throws InvalidArgumentException for invalid log message categories structure.
      *
@@ -149,7 +149,7 @@ public function setExcept(array $except): self
     /**
      * Sets a list of log message levels that current target is interested in.
      *
-     * @param array $levels The list of log message levels.
+     * @param string[] $levels The list of log message levels.
      *
      * @throws InvalidArgumentException for invalid log message level.
      *
@@ -383,7 +383,10 @@ private function filterMessages(array $messages): void
                 continue;
             }
 
-            if ($this->categories->isExcluded($message->context('category', ''))) {
+            /** @var string $category */
+            $category = $message->context('category', '');
+
+            if ($this->categories->isExcluded($category)) {
                 unset($messages[$i]);
                 continue;
             }