diff --git a/src/Psalm/Codebase.php b/src/Psalm/Codebase.php
index 1de35369467..c74ba4637ae 100644
--- a/src/Psalm/Codebase.php
+++ b/src/Psalm/Codebase.php
@@ -793,9 +793,9 @@ public function interfaceHasCorrectCasing(string $fq_interface_name): bool
         return $this->classlikes->interfaceHasCorrectCasing($fq_interface_name);
     }
 
-    public function traitHasCorrectCase(string $fq_trait_name): bool
+    public function traitHasCorrectCasing(string $fq_trait_name): bool
     {
-        return $this->classlikes->traitHasCorrectCase($fq_trait_name);
+        return $this->classlikes->traitHasCorrectCasing($fq_trait_name);
     }
 
     /**
diff --git a/src/Psalm/Internal/Analyzer/ClassAnalyzer.php b/src/Psalm/Internal/Analyzer/ClassAnalyzer.php
index cb4e63491ba..f55fbaaa90d 100644
--- a/src/Psalm/Internal/Analyzer/ClassAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/ClassAnalyzer.php
@@ -1370,7 +1370,7 @@ private function analyzeTraitUse(
                 return false;
             }
 
-            if (!$codebase->traitHasCorrectCase($fq_trait_name)) {
+            if (!$codebase->traitHasCorrectCasing($fq_trait_name)) {
                 if (IssueBuffer::accepts(
                     new UndefinedTrait(
                         'Trait ' . $fq_trait_name . ' has wrong casing',
diff --git a/src/Psalm/Internal/Codebase/ClassLikes.php b/src/Psalm/Internal/Codebase/ClassLikes.php
index f81e888620f..85abeeb0912 100644
--- a/src/Psalm/Internal/Codebase/ClassLikes.php
+++ b/src/Psalm/Internal/Codebase/ClassLikes.php
@@ -131,7 +131,12 @@ class ClassLikes
     /**
      * @var array<lowercase-string, string>
      */
-    private $classlike_aliases = [];
+    private $classlike_aliases_map = [];
+
+    /**
+     * @var array<string, bool>
+     */
+    private $existing_classlike_aliases = [];
 
     /**
      * @var array<string, PhpParser\Node\Stmt\Trait_>
@@ -750,7 +755,7 @@ public function classHasCorrectCasing(string $fq_class_name): bool
             return true;
         }
 
-        if (isset($this->classlike_aliases[strtolower($fq_class_name)])) {
+        if (isset($this->existing_classlike_aliases[$fq_class_name])) {
             return true;
         }
 
@@ -759,7 +764,7 @@ public function classHasCorrectCasing(string $fq_class_name): bool
 
     public function interfaceHasCorrectCasing(string $fq_interface_name): bool
     {
-        if (isset($this->classlike_aliases[strtolower($fq_interface_name)])) {
+        if (isset($this->existing_classlike_aliases[$fq_interface_name])) {
             return true;
         }
 
@@ -768,16 +773,16 @@ public function interfaceHasCorrectCasing(string $fq_interface_name): bool
 
     public function enumHasCorrectCasing(string $fq_enum_name): bool
     {
-        if (isset($this->classlike_aliases[strtolower($fq_enum_name)])) {
+        if (isset($this->existing_classlike_aliases[$fq_enum_name])) {
             return true;
         }
 
         return isset($this->existing_enums[$fq_enum_name]);
     }
 
-    public function traitHasCorrectCase(string $fq_trait_name): bool
+    public function traitHasCorrectCasing(string $fq_trait_name): bool
     {
-        if (isset($this->classlike_aliases[strtolower($fq_trait_name)])) {
+        if (isset($this->existing_classlike_aliases[$fq_trait_name])) {
             return true;
         }
 
@@ -820,12 +825,10 @@ public function getTraitNode(string $fq_trait_name): PhpParser\Node\Stmt\Trait_
         throw new UnexpectedValueException('Could not locate trait statement');
     }
 
-    /**
-     * @param lowercase-string $alias_name
-     */
     public function addClassAlias(string $fq_class_name, string $alias_name): void
     {
-        $this->classlike_aliases[$alias_name] = $fq_class_name;
+        $this->classlike_aliases_map[strtolower($alias_name)] = $fq_class_name;
+        $this->existing_classlike_aliases[$alias_name] = true;
     }
 
     public function getUnAliasedName(string $alias_name): string
@@ -835,7 +838,7 @@ public function getUnAliasedName(string $alias_name): string
             return $alias_name;
         }
 
-        $result = $this->classlike_aliases[$alias_name_lc] ?? $alias_name;
+        $result = $this->classlike_aliases_map[$alias_name_lc] ?? $alias_name;
         if ($result === $alias_name) {
             return $result;
         }
diff --git a/src/Psalm/Internal/Codebase/Scanner.php b/src/Psalm/Internal/Codebase/Scanner.php
index fb6e1bf5c63..b45044a0431 100644
--- a/src/Psalm/Internal/Codebase/Scanner.php
+++ b/src/Psalm/Internal/Codebase/Scanner.php
@@ -605,7 +605,7 @@ private function scanFile(
             }
 
             foreach ($file_storage->classlikes_in_file as $fq_classlike_name) {
-                $this->codebase->exhumeClassLikeStorage(strtolower($fq_classlike_name), $file_path);
+                $this->codebase->exhumeClassLikeStorage($fq_classlike_name, $file_path);
             }
 
             foreach ($file_storage->required_classes as $fq_classlike_name) {
@@ -736,7 +736,7 @@ function () use ($fq_class_name): ?ReflectionClass {
         $new_fq_class_name_lc = strtolower($new_fq_class_name);
 
         if ($new_fq_class_name_lc !== $fq_class_name_lc) {
-            $classlikes->addClassAlias($new_fq_class_name, $fq_class_name_lc);
+            $classlikes->addClassAlias($new_fq_class_name, $fq_class_name);
             $fq_class_name_lc = $new_fq_class_name_lc;
         }
 
diff --git a/src/Psalm/Internal/PhpVisitor/Reflector/ExpressionScanner.php b/src/Psalm/Internal/PhpVisitor/Reflector/ExpressionScanner.php
index 2a6dbf71eb9..3cc4bd7350b 100644
--- a/src/Psalm/Internal/PhpVisitor/Reflector/ExpressionScanner.php
+++ b/src/Psalm/Internal/PhpVisitor/Reflector/ExpressionScanner.php
@@ -257,8 +257,6 @@ private static function registerClassMapFunctionCall(
                     $second_arg_value = substr($second_arg_value, 1);
                 }
 
-                $second_arg_value = strtolower($second_arg_value);
-
                 $codebase->classlikes->addClassAlias(
                     $first_arg_value,
                     $second_arg_value
diff --git a/src/Psalm/Storage/FileStorage.php b/src/Psalm/Storage/FileStorage.php
index df09117dbea..fcde3b3a6ad 100644
--- a/src/Psalm/Storage/FileStorage.php
+++ b/src/Psalm/Storage/FileStorage.php
@@ -86,7 +86,7 @@ class FileStorage
     public $type_aliases = [];
 
     /**
-     * @var array<lowercase-string, string>
+     * @var array<string, string>
      */
     public $classlike_aliases = [];
 
diff --git a/tests/Internal/Codebase/ClassLikesTest.php b/tests/Internal/Codebase/ClassLikesTest.php
index b04beb38f41..8168d17a875 100644
--- a/tests/Internal/Codebase/ClassLikesTest.php
+++ b/tests/Internal/Codebase/ClassLikesTest.php
@@ -30,7 +30,7 @@ public function setUp(): void
 
     public function testWillDetectClassImplementingAliasedInterface(): void
     {
-        $this->classlikes->addClassAlias('Foo', 'bar');
+        $this->classlikes->addClassAlias('Foo', 'Bar');
 
         $classStorage = new ClassLikeStorage('Baz');
         $classStorage->class_implements['bar'] = 'Bar';
@@ -42,9 +42,9 @@ public function testWillDetectClassImplementingAliasedInterface(): void
 
     public function testWillResolveAliasedAliases(): void
     {
-        $this->classlikes->addClassAlias('Foo', 'bar');
-        $this->classlikes->addClassAlias('Bar', 'baz');
-        $this->classlikes->addClassAlias('Baz', 'qoo');
+        $this->classlikes->addClassAlias('Foo', 'Bar');
+        $this->classlikes->addClassAlias('Bar', 'Baz');
+        $this->classlikes->addClassAlias('Baz', 'Qoo');
 
         self::assertSame('Foo', $this->classlikes->getUnAliasedName('Qoo'));
     }