1 files changed, 2 insertions, 3 deletions

diff --git a/src/xfns.c b/src/xfns.c
index 4d41c81b1cc..194b355d3a4 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -717,9 +717,8 @@ x_set_frame_parameters (f, alist)
           param_index = Fget (prop, Qx_frame_parameter);
           old_value = get_frame_param (f, prop);
           store_frame_param (f, prop, val);
-          if (INTEGERP (param_index)
-              && XINT (param_index) >= 0
-              && (XINT (param_index)
+          if (NATNUMP (param_index)
+              && (XFASTINT (param_index)
                   < sizeof (x_frame_parms)/sizeof (x_frame_parms[0])))
             (*x_frame_parms[XINT (param_index)].setter)(f, val, old_value);
         }