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 9d5ed21ca..765535b82 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php
@@ -4,6 +4,7 @@ namespace Psalm\Internal\Analyzer\Statements\Expression\Call\Method;
 use PhpParser;
 use Psalm\Internal\Analyzer\ClassLikeAnalyzer;
 use Psalm\Internal\Analyzer\StatementsAnalyzer;
+use Psalm\Internal\Analyzer\Statements\Expression\Call\ClassTemplateParamCollector;
 use Psalm\Codebase;
 use Psalm\CodeLocation;
 use Psalm\Context;
@@ -145,16 +146,83 @@ class MethodCallPurityAnalyzer
                     && isset($context->vars_in_scope[$mutation_var_id])
                     && !isset($class_storage->declaring_property_ids[$name]);
 
-                $current_context = $context;
-
-                do {
-                    $current_context->remove($mutation_var_id);
-                } while ($current_context = $current_context->parent_context);
-
                 if ($this_property_didnt_exist) {
                     $context->vars_in_scope[$mutation_var_id] = Type::getMixed();
+                } else {
+                    $context->vars_in_scope[$mutation_var_id] = self::getExpandedPropertyType(
+                        $codebase,
+                        $class_storage->name,
+                        $name,
+                        $class_storage
+                    ) ?: Type::getMixed();
                 }
             }
         }
     }
+
+    private static function getExpandedPropertyType(
+        Codebase $codebase,
+        string $fq_class_name,
+        string $property_name,
+        \Psalm\Storage\ClassLikeStorage $storage
+    ) : ?Type\Union {
+        $property_class_name = $codebase->properties->getDeclaringClassForProperty(
+            $fq_class_name . '::$' . $property_name,
+            true
+        );
+
+        if ($property_class_name === null) {
+            return null;
+        }
+
+        $property_class_storage = $codebase->classlike_storage_provider->get($property_class_name);
+
+        $property_storage = $property_class_storage->properties[$property_name];
+
+        if (!$property_storage->type) {
+            return null;
+        }
+
+        $property_type = clone $property_storage->type;
+
+        $fleshed_out_type = !$property_type->isMixed()
+            ? \Psalm\Internal\Type\TypeExpander::expandUnion(
+                $codebase,
+                $property_type,
+                $fq_class_name,
+                $fq_class_name,
+                $storage->parent_class,
+                true,
+                false,
+                $storage->final
+            )
+            : $property_type;
+
+        $class_template_params = ClassTemplateParamCollector::collect(
+            $codebase,
+            $property_class_storage,
+            $storage,
+            null,
+            new Type\Atomic\TNamedObject($fq_class_name),
+            true
+        );
+
+        $template_result = new \Psalm\Internal\Type\TemplateResult(
+            $class_template_params ?: [],
+            []
+        );
+
+        if ($class_template_params) {
+            $fleshed_out_type = \Psalm\Internal\Type\TemplateStandinTypeReplacer::replace(
+                $fleshed_out_type,
+                $template_result,
+                $codebase,
+                null,
+                null,
+                null
+            );
+        }
+
+        return $fleshed_out_type;
+    }
 }