diff --git a/src/userfunc.c b/src/userfunc.c
index ef1d42d..3c2673d 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -200,6 +200,7 @@
 	    {
 		typval_T	rettv;
 
+		// find the end of the expression (doesn't evaluate it)
 		any_default = TRUE;
 		p = skipwhite(p) + 1;
 		p = skipwhite(p);