--- freebsd/zstd_kfreebsd.h     (revision 327712)
+++ freebsd/zstd_kfreebsd.h     (working copy)
@@ -49,6 +49,27 @@
 #define calloc(a,b)    (malloc)((a)*(b), M_ZSTD, M_WAITOK | M_ZERO)
 #endif

+#if defined(__mips__) || defined(__riscv)
+#undef __ctzsi2
+#undef __ctzdi2
+
+static inline unsigned
+__ctzsi2(unsigned x)
+{
+       if (x == 0)
+               return (sizeof(x) * NBBY);
+       return (ffsl(x) - 1);
+}
+
+static inline unsigned long long
+__ctzdi2(unsigned long long x)
+{
+       if (x == 0)
+               return (sizeof(x) * NBBY);
+       return (ffsll(x) - 1);
+}
+#endif /* __mips__ || __riscv */
+
 #ifdef __cplusplus
 }
 #endif