diff --git a/src/core/nm-core-utils.c b/src/core/nm-core-utils.c
index 15cf4d8183..bae9c336e6 100644
--- a/src/core/nm-core-utils.c
+++ b/src/core/nm-core-utils.c
@@ -585,7 +585,7 @@ static gulong
 _sleep_duration_convert_ms_to_us(guint32 sleep_duration_msec)
 {
     if (sleep_duration_msec > 0) {
-        guint64 x = (gint64) sleep_duration_msec * (guint64) 1000L;
+        guint64 x = ((guint64) sleep_duration_msec) * 1000UL;
 
         return x < G_MAXULONG ? (gulong) x : G_MAXULONG;
     }