diff --git a/src/Psalm/Internal/Analyzer/MethodComparator.php b/src/Psalm/Internal/Analyzer/MethodComparator.php
index c18fe47f883..61726c5adbe 100644
--- a/src/Psalm/Internal/Analyzer/MethodComparator.php
+++ b/src/Psalm/Internal/Analyzer/MethodComparator.php
@@ -7,6 +7,7 @@
 use Psalm\CodeLocation;
 use Psalm\Codebase;
 use Psalm\Config;
+use Psalm\Internal\Codebase\InternalCallMapHandler;
 use Psalm\Internal\FileManipulation\FileManipulationBuffer;
 use Psalm\Internal\MethodIdentifier;
 use Psalm\Internal\PhpVisitor\ParamReplacementVisitor;
@@ -117,13 +118,13 @@ public static function compare(
             );
         }
 
+        // CallMapHandler needed due to https://github.com/vimeo/psalm/issues/10378
         if (!$guide_classlike_storage->user_defined
             && $implementer_classlike_storage->user_defined
             && $codebase->analysis_php_version_id >= 8_01_00
-            && ($guide_method_storage->return_type
+            && (($guide_method_storage->return_type && InternalCallMapHandler::inCallMap($cased_guide_method_id))
                 || $guide_method_storage->signature_return_type
-            )
-            && !$implementer_method_storage->signature_return_type
+            ) && !$implementer_method_storage->signature_return_type
             && !array_filter(
                 $implementer_method_storage->attributes,
                 static fn(AttributeStorage $s): bool => $s->fq_class_name === 'ReturnTypeWillChange',
@@ -944,7 +945,13 @@ private static function compareMethodSignatureReturnTypes(
             : UnionTypeComparator::isContainedByInPhp($implementer_signature_return_type, $guide_signature_return_type);
 
         if (!$is_contained_by) {
-            if ($codebase->analysis_php_version_id >= 8_00_00
+            if ($implementer_signature_return_type === null
+                && array_filter(
+                    $implementer_method_storage->attributes,
+                    static fn(AttributeStorage $s): bool => $s->fq_class_name === 'ReturnTypeWillChange',
+                )) {
+                // no error if return type will change and no signature set at all
+            } elseif ($codebase->analysis_php_version_id >= 8_00_00
                       || $guide_classlike_storage->is_trait === $implementer_classlike_storage->is_trait
                       || !in_array($guide_classlike_storage->name, $implementer_classlike_storage->used_traits)
                       || $implementer_method_storage->defining_fqcln !== $implementer_classlike_storage->name
diff --git a/tests/AttributeTest.php b/tests/AttributeTest.php
index 18d82b04ec4..f1051773882 100644
--- a/tests/AttributeTest.php
+++ b/tests/AttributeTest.php
@@ -252,6 +252,32 @@ public function getIterator()
                 'ignored_issues' => [],
                 'php_version' => '8.1',
             ],
+            'returnTypeWillChangeNoSignatureType' => [
+                'code' => '<?php
+                    class Foo {
+                        /**
+                         * @param array<string> $arg
+                         * @return string
+                         */
+                        public function run($arg) : string {
+                            return implode("s", $arg);
+                        }
+                    }
+
+                    class Bar extends Foo {
+                        /**
+                         * @param array<string> $arg
+                         * @return string
+                         */
+                        #[ReturnTypeWillChange]
+                        public function run($arg) {
+                            return implode(" ", $arg);
+                        }
+                    }',
+                'assertions' => [],
+                'ignored_issues' => [],
+                'php_version' => '8.1',
+            ],
             'allowDynamicProperties' => [
                 'code' => '<?php