--- a/src/postgres/include/storage/s_lock.h
+++ b/src/postgres/include/storage/s_lock.h
@@ -293,6 +293,29 @@ spin_delay(void)
 #endif	 /* __arm__ || __arm || __aarch64__ */
 
 
+/*
+ * RISC-V likewise uses __sync_lock_test_and_set(int *, int) if available.
+ */
+#if defined(__riscv)
+#ifdef HAVE_GCC__SYNC_INT32_TAS
+#define HAS_TEST_AND_SET
+
+#define TAS(lock) tas(lock)
+
+typedef int slock_t;
+
+static __inline__ int
+tas(volatile slock_t *lock)
+{
+       return __sync_lock_test_and_set(lock, 1);
+}
+
+#define S_UNLOCK(lock) __sync_lock_release(lock)
+
+#endif  /* HAVE_GCC__SYNC_INT32_TAS */
+#endif  /* __riscv */
+
+
 /* S/390 and S/390x Linux (32- and 64-bit zSeries) */
 #if defined(__s390__) || defined(__s390x__)
 #define HAS_TEST_AND_SET
