diff --git a/external/CMakeLists.txt b/external/CMakeLists.txt
index c9cf142db..fab231db5 100644
--- a/external/CMakeLists.txt
+++ b/external/CMakeLists.txt
@@ -136,6 +136,10 @@ if(SLANG_INCLUDE_INSTALL)
     DIRECTORY ${PROJECT_SOURCE_DIR}/external/ieee1800/
     DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/ieee1800
     COMPONENT slang_Development)
+  install(
+    FILES ${PROJECT_SOURCE_DIR}/external/expected.hpp
+    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+    COMPONENT slang_Development)
 
   if(NOT fmt_FOUND)
     install(