diff --git a/CMakeLists.txt b/CMakeLists.txt
index ae9c5692..e5e2e317 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,7 +17,7 @@ endif ()
 
 # Joins arguments and places the results in ${result_var}.
 function(join result_var)
-  set(result )
+  set(result "")
   foreach (arg ${ARGN})
     set(result "${result}${arg}")
   endforeach ()