diff --git a/CMakeLists.txt b/CMakeLists.txt
index c60b032..d2c353b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -73,7 +73,7 @@ if("${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
     
     set(BUILD_TESTING ON)
     
-    install(FILES asio_compatibility.hpp server_http.hpp client_http.hpp server_https.hpp client_https.hpp crypto.hpp utility.hpp status_code.hpp DESTINATION include/simple-web-server)
+    install(FILES asio_compatibility.hpp server_http.hpp client_http.hpp server_https.hpp client_https.hpp crypto.hpp utility.hpp status_code.hpp mutex.hpp DESTINATION include/simple-web-server)
 endif()
 
 if(BUILD_TESTING)