diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4eecb5d..54198bc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,7 +7,7 @@ ExternalProject_Add(tools
     CMAKE_ARGS
         -D CMAKE_INSTALL_PREFIX=${TOOLS_PREFIX})
 
-project(rts)
+project(rts C)
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_SOURCE_DIR}/cmake)
 
 if(CMAKE_TOOLCHAIN_FILE MATCHES "ps1")