diff --git a/src/userfunc.c b/src/userfunc.c
index 9393b62..a70870b 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -664,6 +664,8 @@
 		if (fp->uf_ret_type == NULL)
 		    goto errret;
 	    }
+	    else
+		fp->uf_ret_type = &t_unknown;
 	}
 
 	fp->uf_lines = newlines;