diff --git a/exec/main.c b/exec/main.c
index 548f7095..b0d0461a 100644
--- a/exec/main.c
+++ b/exec/main.c
@@ -473,7 +473,7 @@ void main_get_config_modules(struct config_iface_ver0 ***modules, int *num)
 }
 
 int main_mcast (
-        struct iovec *iovec,
+        const struct iovec *iovec,
         unsigned int iov_len,
         unsigned int guarantee)
 {
diff --git a/exec/main.h b/exec/main.h
index 55885134..3035200f 100644
--- a/exec/main.h
+++ b/exec/main.h
@@ -7,7 +7,7 @@
  * Author: Steven Dake (sdake@redhat.com)
  *
  * This software licensed under BSD license, the text of which follows:
- * 
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
@@ -56,7 +56,7 @@ extern unsigned long long *(*main_clm_get_by_nodeid) (unsigned int node_id);
 extern void main_get_config_modules(struct config_iface_ver0 ***modules, int *num);
 
 extern int main_mcast (
-	struct iovec *iovec,
+	const struct iovec *iovec,
 	unsigned int iov_len,
 	unsigned int guarantee);
 
diff --git a/include/corosync/engine/coroapi.h b/include/corosync/engine/coroapi.h
index 25375573..13e07ad0 100644
--- a/include/corosync/engine/coroapi.h
+++ b/include/corosync/engine/coroapi.h
@@ -415,8 +415,8 @@ struct corosync_api_v1 {
 
 	int (*totem_ring_reenable) (void);
 
-	/* FIXME: const iovec? */
-	int (*totem_mcast) (struct iovec *iovec, unsigned int iov_len, unsigned int guarantee);
+	int (*totem_mcast) (const struct iovec *iovec,
+			    unsigned int iov_len, unsigned int guarantee);
 
 	int (*totem_ifaces_get) (
 		unsigned int nodeid,