diff --git a/lib/other/setgroups.c b/lib/other/setgroups.c
index 62e356623..e1813b0ca 100644
--- a/lib/other/setgroups.c
+++ b/lib/other/setgroups.c
@@ -9,7 +9,7 @@ int setgroups(int ngroups, const gid_t *gidset)
 {
   message m;
 
-  m.m1_p1 = gidset;
+  m.m1_p1 = (char *) gidset;
   m.m1_i1 = ngroups;
 
   return(_syscall(MM, SETGROUPS, &m));