diff --git a/src/backend/threads.c b/src/backend/threads.c
index ded04a60e..dfbcdadfe 100644
--- a/src/backend/threads.c
+++ b/src/backend/threads.c
@@ -257,7 +257,7 @@ lumiera_thread_deadline_extend (unsigned ms)
       clock_gettime (CLOCK_REALTIME, &deadline);
       deadline.tv_sec += ms / 1000;
       deadline.tv_nsec += 1000000 * (ms % 1000);
-      if (deadline.tv_nsec > 1000000000)
+      if (deadline.tv_nsec >= 1000000000)
         {
           deadline.tv_sec += (deadline.tv_nsec / 1000000000);
           deadline.tv_nsec %= 1000000000;
diff --git a/src/lib/sync.hpp b/src/lib/sync.hpp
index 6cd0cd294..1d40cf96f 100644
--- a/src/lib/sync.hpp
+++ b/src/lib/sync.hpp
@@ -344,7 +344,7 @@ namespace lib {
                   clock_gettime(CLOCK_REALTIME, this);
                   tv_sec   += offs / 1000;
                   tv_nsec  += 1000000 * (offs % 1000);
-                  if (tv_nsec > 1000000000)
+                  if (tv_nsec >= 1000000000)
                     {
                       tv_sec += tv_nsec / 1000000000;
                       tv_nsec %= 1000000000;