diff --git a/src/core/nm-core-utils.c b/src/core/nm-core-utils.c
index bae9c336e6..f6690846d3 100644
--- a/src/core/nm-core-utils.c
+++ b/src/core/nm-core-utils.c
@@ -587,7 +587,8 @@ _sleep_duration_convert_ms_to_us(guint32 sleep_duration_msec)
     if (sleep_duration_msec > 0) {
         guint64 x = ((guint64) sleep_duration_msec) * 1000UL;
 
-        return x < G_MAXULONG ? (gulong) x : G_MAXULONG;
+        nm_assert(x < G_MAXULONG);
+        return x;
     }
     return G_USEC_PER_SEC / 20;
 }