diff --git a/include/compat/sys/time.h b/include/compat/sys/time.h
index 235bc6e..3d31985 100644
--- a/include/compat/sys/time.h
+++ b/include/compat/sys/time.h
@@ -13,4 +13,20 @@ int gettimeofday(struct timeval *tp, void *tzp);
 #include_next <sys/time.h>
 #endif
 
+#ifndef CLOCK_MONOTONIC
+#define CLOCK_MONOTONIC CLOCK_REALTIME
+#endif
+
+#ifndef timersub
+#define timersub(tvp, uvp, vvp)                                         \
+	do {                                                            \
+		(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--;                                \
+			(vvp)->tv_usec += 1000000;                      \
+		}                                                       \
+	} while (0)
+#endif
+
 #endif