diff --git a/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeDocblockScanner.php b/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeDocblockScanner.php
index 5452d899e6b..14eddc5d5a3 100644
--- a/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeDocblockScanner.php
+++ b/src/Psalm/Internal/PhpVisitor/Reflector/FunctionLikeDocblockScanner.php
@@ -615,7 +615,8 @@ private static function getAssertionParts(
                     true
                 ),
                 null,
-                $template_types
+                $template_types,
+                $type_aliases
             );
         } catch (TypeParseTreeException $e) {
             $storage->docblock_issues[] = new InvalidDocblock(
diff --git a/tests/TypeAnnotationTest.php b/tests/TypeAnnotationTest.php
index ee512e26bcc..c55a5911221 100644
--- a/tests/TypeAnnotationTest.php
+++ b/tests/TypeAnnotationTest.php
@@ -593,6 +593,43 @@ class C extends A {}
                     '$output' => 'string',
                 ],
             ],
+            'importedTypeUsedInAssertion' => [
+                'code' => '<?php
+                    /** @psalm-type Foo = string */
+                    class A {}
+
+                    /**
+                     * @psalm-immutable
+                     * @psalm-import-type Foo from A as FooAlias
+                     */
+                    class B {
+                        /**
+                         * @param mixed $input
+                         * @psalm-return FooAlias
+                         */
+                        public function convertToFoo($input) {
+                            $this->assertFoo($input);
+                            return $input;
+                        }
+
+                        /**
+                         * @param mixed $value
+                         * @psalm-assert FooAlias $value
+                         */
+                        private function assertFoo($value): void {
+                            if(!is_string($value)) {
+                                throw new \InvalidArgumentException();
+                            }
+                        }
+                    }
+
+                    $instance = new B();
+                    $output = $instance->convertToFoo("hallo");
+                ',
+                'assertions' => [
+                    '$output' => 'string',
+                ]
+            ]
         ];
     }