diff --git a/libc/include/sys/ucontext.h b/libc/include/sys/ucontext.h
index 8e5873d..cefe177 100644
--- a/libc/include/sys/ucontext.h
+++ b/libc/include/sys/ucontext.h
@@ -316,6 +316,8 @@
 
 #define NGREG 32
 
+#if defined(__USE_GNU)
+
 #define REG_PC 0
 #define REG_RA 1
 #define REG_SP 2
@@ -323,6 +325,8 @@
 #define REG_S0 8
 #define REG_A0 10
 
+#endif // defined(__USE_GNU)
+
 typedef unsigned long __riscv_mc_gp_state[NGREG];
 
 typedef unsigned long greg_t;