diff --git a/CMakeLists.txt b/CMakeLists.txt
index bfe2542bb31e7ad9d48ab9668d0321fb3ad29ae9..3de978ecbac79d955e1213e5ed18990e56b894db 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -216,11 +216,10 @@ SET(KWSYS_CLASSES)
 SET(KWSYS_H_FILES Configure)
 SET(KWSYS_HXX_FILES Configure)
 
-# Enforce component dependencies (none currently exists).
-#IF(KWSYS_USE_SystemTools)
-#  SET(KWSYS_USE_Directory 1)
-#  SET(KWSYS_USE_RegularExpression 1)
-#ENDIF(KWSYS_USE_SystemTools)
+# Enforce component dependencies.
+IF(KWSYS_USE_SystemTools)
+  SET(KWSYS_USE_Directory 1)
+ENDIF(KWSYS_USE_SystemTools)
 
 # Add selected C++ classes.
 FOREACH(c Directory RegularExpression SystemTools)