config/output: correct refresh rate rounding error

1 files changed, 4 insertions, 1 deletions

diff --git a/sway/config/output.c b/sway/config/output.c
index b59cabd4..c9ec6745 100644
--- a/sway/config/output.c
+++ b/sway/config/output.c
@@ -237,7 +237,10 @@ struct output_config *store_output_config(struct output_config *oc) {
 
 static void set_mode(struct wlr_output *output, int width, int height,
                 float refresh_rate, bool custom) {
-        int mhz = (int)(refresh_rate * 1000);
+        // Not all floating point integers can be represented exactly
+        // as (int)(1000 * mHz / 1000.f)
+        // round() the result to avoid any error
+        int mhz = (int)round(refresh_rate * 1000);
 
         if (wl_list_empty(&output->modes) || custom) {
                 sway_log(SWAY_DEBUG, "Assigning custom mode to %s", output->name);