diff --git a/libguile/options.h b/libguile/options.h
index 57b552d38..a40a6a575 100644
--- a/libguile/options.h
+++ b/libguile/options.h
@@ -60,7 +60,7 @@ typedef struct scm_option
     schizophrenic use: both SCM and int
    */
   unsigned long val;
-  // SCM val
+  /* SCM val */
   char *doc;
 } scm_option;