diff --git a/riscos/window.c b/riscos/window.c
index dc99f1d8a..cefd90df8 100644
--- a/riscos/window.c
+++ b/riscos/window.c
@@ -445,7 +445,7 @@ void ro_gui_throb(void)
           {
             g->throbtime = nowtime;
             g->throbber++;
-            if (theme_throbs < (float)g->throbber)
+            if (theme_throbs < (unsigned int)g->throbber)
               g->throbber = 0;
             sprintf(g->throb_buf, "throbber%u", g->throbber);
             wimp_set_icon_state(g->data.browser.toolbar,