diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php
index 1b5859bd660..0fde9d86617 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php
@@ -158,7 +158,7 @@ public static function analyze(
                     && !isset($class_storage->declaring_property_ids[$name]);
 
                 if ($this_property_didnt_exist) {
-                    $context->vars_in_scope[$mutation_var_id] = Type::getMixed();
+                    unset($context->vars_in_scope[$mutation_var_id]);
                 } else {
                     $new_type = AssignmentAnalyzer::getExpandedPropertyType(
                         $codebase,
diff --git a/tests/MagicPropertyTest.php b/tests/MagicPropertyTest.php
index a6b9876dd27..445b3ee1f12 100644
--- a/tests/MagicPropertyTest.php
+++ b/tests/MagicPropertyTest.php
@@ -731,6 +731,41 @@ public function __set(string $_prop, $_value) {}
                     $a->type = A::TYPE_B;
                 ',
             ],
+            'impureMethodTest' => [
+                'code' => '<?php
+                    /**
+                     * @property array<string, string> $errors
+                     *
+                     * @psalm-seal-properties
+                     */
+                    final class OrganizationObject {
+
+                        public function __get(string $key)
+                        {
+                            return [];
+                        }
+
+                        /**
+                         * @param mixed $a
+                         */
+                        public function __set(string $key, $a): void
+                        {
+                        }
+
+                        public function updateErrors(): void {
+                            /** @var array<string, string> */
+                            $errors = [];
+                            $this->errors = $errors;
+                        }
+                        /** @return array<string, string> */
+                        public function updateStatus(): array {
+                            $_ = $this->errors;
+                            $this->updateErrors();
+                            $errors = $this->errors;
+                            return $errors;
+                        }
+                    }'
+            ]
         ];
     }