diff --git a/CMakeLists.txt b/CMakeLists.txt
index fb2ecae..8fc6649 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required (VERSION 3.1)
-project (TRLIB VERSION 0.4)
+project (TRLIB VERSION 0.4 LANGUAGES C)
 
 set(PROJECT_DESCRIPTION "Trust Region Subproblem Solver Library")