diff --git a/etc/spack/defaults/modules.yaml b/etc/spack/defaults/modules.yaml
index 55b1f0af7b..27450b4259 100644
--- a/etc/spack/defaults/modules.yaml
+++ b/etc/spack/defaults/modules.yaml
@@ -40,8 +40,9 @@ modules:
     roots:
      tcl:    $spack/share/spack/modules
      lmod:   $spack/share/spack/lmod
-    # What type of modules to use ("tcl" and/or "lmod")
-    enable: []
+    # What type of modules to use
+    enable:
+      - tcl
 
     tcl:
       all: