diff --git a/include/sys/time.h b/include/sys/time.h
index 7b1e15e9b5f..3d7139e7547 100644
--- a/include/sys/time.h
+++ b/include/sys/time.h
@@ -77,13 +77,13 @@
 #define timersub(tvp, uvp, vvp) \
   do \
     { \
-      (vvp)->tv_sec = (tvp)->tv_sec - (uvp)->tv_sec; \
-      if ((uvp)->tv_usec > (tvp)->tv_usec) \
+      (vvp)->tv_sec = (tvp)->tv_sec - (uvp)->tv_sec; \
+      (vvp)->tv_usec = (tvp)->tv_usec - (uvp)->tv_usec; \
+      if ((vvp)->tv_usec < 0) \
         { \
-          (vvp)->tv_sec--; \
-          (tvp)->tv_usec += 1000000; \
-        } \
-      (vvp)->tv_usec = (tvp)->tv_usec - (uvp)->tv_usec; \
+          (vvp)->tv_sec--; \
+          (vvp)->tv_usec += 1000000; \
+        } \
     } \
   while (0)
 
@@ -92,8 +92,8 @@
 #define timerclear(tvp) \
   do \
     { \
-      tvp)->tv_sec = 0; \
-      tvp)->tv_usec = 0; \
+      (tvp)->tv_sec = 0; \
+      (tvp)->tv_usec = 0; \
     } \
   while (0)