1 files changed, 3 insertions, 0 deletions
diff --git a/process.c b/process.c
index 972c9e8eed..6c06c2b6bb 100644
--- a/process.c
+++ b/process.c
@@ -1283,6 +1283,9 @@ proc_setgroups(VALUE obj, VALUE ary)
 	    }
 	    else {
 		gr = getgrnam(RSTRING(g)->ptr);
+		if (gr == NULL)
+		    rb_raise(rb_eArgError, "can't find group for %s", RSTRING(g)->ptr);
+		groups[i] = gr->gr_gid;
 	    }
 	}
     }